Warning about deprecated `quarkus.resteasy.metrics.enabled` is printed even when replacement setting is already used
### Describe the bug

On every dev mode start of my application, I get this warning:
```
2021-08-18 14:26:23,873 WARN  [io.qua.sma.met.dep.SmallRyeMetricsProcessor] (build-42) `quarkus.resteasy.metrics.enabled` is deprecated and will be removed in a future version. Use `quarkus.smallrye-metrics.jaxrs.enabled` to enable metrics for REST endpoints using the smallrye-metrics extension
```

This warning is not right, my configuration specifies only the new property:
```
quarkus.smallrye-metrics.jaxrs.enabled=true
```

### Expected behavior

No warning should be printed in this case, since I already use the new setting.

### Actual behavior

Listening for transport dt_socket at address: 5005
2021-08-18 14:26:23,873 WARN  [io.qua.sma.met.dep.SmallRyeMetricsProcessor] (build-42) `quarkus.resteasy.metrics.enabled` is deprecated and will be removed in a future version. Use `quarkus.smallrye-metrics.jaxrs.enabled` to enable metrics for REST endpoints using the smallrye-metrics extension
__  ____  __  _____   ___  __ ____  ______
 --/ __ \\/ / / / _ | / _ \\/ //_/ / / / __/
 -/ /_/ / /_/ / __ |/ , _/ ,< / /_/ /\\ \\
--\\___\\_\\____/_/ |_/_/|_/_/|_|\\____/___/
2021-08-18 14:26:26,396 INFO  [io.quarkus] (Quarkus Main Thread) resteasy-multipart-size 1.0.0-SNAPSHOT on JVM (powered by Quarkus 2.1.2.Final) started in 3.240s. Listening on: http://localhost:8080
2021-08-18 14:26:26,399 INFO  [io.quarkus] (Quarkus Main Thread) Profile dev activated. Live Coding activated.
2021-08-18 14:26:26,401 INFO  [io.quarkus] (Quarkus Main Thread) Installed features: [cdi, resteasy, resteasy-jackson, smallrye-context-propagation, smallrye-metrics]


### How to Reproduce?

1. Download the reproducer: 
[resteasy-multipart-size.zip](https://github.com/quarkusio/quarkus/files/7007186/resteasy-multipart-size.zip)
2. mvn quarkus:dev
3. look at the console output

### Output of `uname -a` or `ver`

MSYS_NT-10.0 NANB7NLNVP2 2.10.0(0.325/5/3) 2018-06-13 23:34 x86_64 Msys

### Output of `java -version`

openjdk version "16.0.1" 2021-04-20 OpenJDK Runtime Environment Zulu16.30+15-CA (build 16.0.1+9) OpenJDK 64-Bit Server VM Zulu16.30+15-CA (build 16.0.1+9, mixed mode, sharing)

### GraalVM version (if different from Java)

_No response_

### Quarkus version or git rev

2.1.2.Final

### Build tool (ie. output of `mvnw --version` or `gradlew --version`)

Apache Maven 3.8.1 (05c21c65bdfed0f71a2f2ada8b84da59348c4c5d) Maven home: C:\\eclipse\\tools\\apache-maven\\bin\\.. Java version: 16.0.1, vendor: Azul Systems, Inc., runtime: C:\\eclipse\\tools\\java\\16 Default locale: de_DE, platform encoding: Cp1252 OS name: "windows 10", version: "10.0", arch: "amd64", family: "windows"

### Additional information

_No response_
diff --git a/extensions/resteasy-classic/resteasy-server-common/deployment/src/main/java/io/quarkus/resteasy/server/common/deployment/ResteasyServerCommonProcessor.java b/extensions/resteasy-classic/resteasy-server-common/deployment/src/main/java/io/quarkus/resteasy/server/common/deployment/ResteasyServerCommonProcessor.java
index ed472ecaf1e..e6e19e00900 100755
--- a/extensions/resteasy-classic/resteasy-server-common/deployment/src/main/java/io/quarkus/resteasy/server/common/deployment/ResteasyServerCommonProcessor.java
+++ b/extensions/resteasy-classic/resteasy-server-common/deployment/src/main/java/io/quarkus/resteasy/server/common/deployment/ResteasyServerCommonProcessor.java
@@ -147,11 +147,12 @@ static final class ResteasyConfig {
          * See <a href=
          * "https://github.com/eclipse/microprofile-metrics/blob/2.3.x/spec/src/main/asciidoc/required-metrics.adoc#optional-rest">MicroProfile
          * Metrics: Optional REST metrics</a>.
-         * <p>
-         * Deprecated. Use {@code quarkus.smallrye-metrics.jaxrs.enabled}.
+         *
+         * @deprecated Use {@code quarkus.smallrye-metrics.jaxrs.enabled} instead.
          */
-        @ConfigItem(name = "metrics.enabled", defaultValue = "false")
-        public boolean metricsEnabled;
+        @Deprecated(forRemoval = true)
+        @ConfigItem(name = "metrics.enabled")
+        public Optional<Boolean> metricsEnabled;
 
         /**
          * Ignore all explicit JAX-RS {@link Application} classes.
diff --git a/extensions/smallrye-metrics/deployment/src/main/java/io/quarkus/smallrye/metrics/deployment/JaxRsMetricsProcessor.java b/extensions/smallrye-metrics/deployment/src/main/java/io/quarkus/smallrye/metrics/deployment/JaxRsMetricsProcessor.java
index d86b4d39fc0..f9252e5b0b3 100644
--- a/extensions/smallrye-metrics/deployment/src/main/java/io/quarkus/smallrye/metrics/deployment/JaxRsMetricsProcessor.java
+++ b/extensions/smallrye-metrics/deployment/src/main/java/io/quarkus/smallrye/metrics/deployment/JaxRsMetricsProcessor.java
@@ -32,7 +32,7 @@ static class RestMetricsEnabled implements BooleanSupplier {
         SmallRyeMetricsProcessor.SmallRyeMetricsConfig smConfig;
 
         public boolean getAsBoolean() {
-            boolean resteasyConfigEnabled = ConfigProvider.getConfig().getOptionalValue(RESTEASY_CONFIG_PROPERTY, boolean.class)
+            boolean resteasyConfigEnabled = ConfigProvider.getConfig().getOptionalValue(RESTEASY_CONFIG_PROPERTY, Boolean.class)
                     .orElse(false);
             return smConfig.extensionsEnabled && (smConfig.jaxrsEnabled || resteasyConfigEnabled);
         }
@@ -73,7 +73,7 @@ void enableMetrics(Optional<MetricsCapabilityBuildItem> metricsCapabilityBuildIt
     }
 
     private void warnIfDeprecatedResteasyPropertiesPresent() {
-        if (ConfigProvider.getConfig().getOptionalValue(RESTEASY_CONFIG_PROPERTY, boolean.class).isPresent()) {
+        if (ConfigProvider.getConfig().getOptionalValue(RESTEASY_CONFIG_PROPERTY, Boolean.class).isPresent()) {
             SmallRyeMetricsProcessor.LOGGER.warn(
                     "`quarkus.resteasy.metrics.enabled` is deprecated and will be removed in a future version. "
                             + "Use `quarkus.smallrye-metrics.jaxrs.enabled` to enable metrics for REST endpoints "
['extensions/resteasy-classic/resteasy-server-common/deployment/src/main/java/io/quarkus/resteasy/server/common/deployment/ResteasyServerCommonProcessor.java', 'extensions/smallrye-metrics/deployment/src/main/java/io/quarkus/smallrye/metrics/deployment/JaxRsMetricsProcessor.java']