[LMA Regression] redshift get_catalog requires exactly one database
### Describe the bug
Users are seeing the `redshift get_catalog requires exactly one database` error on dbt v0.15.0-rc1 even though they only have a single database specified in their project.

### Steps To Reproduce
Exact reproduction case tbd
diff --git a/core/dbt/adapters/base/relation.py b/core/dbt/adapters/base/relation.py
index d429fb7f3..957ac3802 100644
--- a/core/dbt/adapters/base/relation.py
+++ b/core/dbt/adapters/base/relation.py
@@ -246,7 +246,10 @@ class BaseRelation(FakeAPIObject, Hashable):
         if not isinstance(view_name, str):
             view_name = None
 
-        return InformationSchema.from_relation(self, view_name)
+        # Kick the user-supplied schema out of the information schema relation
+        # Instead address this as <database>.information_schema by default
+        info_schema = InformationSchema.from_relation(self, view_name)
+        return info_schema.incorporate(path={"schema": None})
 
     def information_schema_only(self) -> 'InformationSchema':
         return self.information_schema()
['core/dbt/adapters/base/relation.py']