Email alerts coming without subject (and alert name too long)
**Impact of the bug**
Any system using the new AlertManager module (only MicroServices so far)

**Describe the bug**
Over the weekend I received 3 MSTransferor email alerts with no subject `(no subject)`. We should adopt the correct alert arguments such that alert emails are sent with a meaningful and short subject.

**How to reproduce it**
I guess it's just a matter of creating an alert in AlertManager.

**Expected behavior**
There are a couple of things to be fixed in this issue:
* email alerts must contain a short and meaningful subject. Something like "MSTransferor: input transfer over threshold for workflow ABC..."
* the set of rule ids should likely not be part of the alert name (otherwise it's very hard to see them in Slack)

**Additional context and error message**
Follow up of: https://github.com/dmwm/WMCore/pull/10308
Screenshot (cropped): http://amaltaro.web.cern.ch/amaltaro/forWMCore/Issue_10468/wrong_alert_email.png
diff --git a/src/python/WMCore/MicroService/MSTransferor/MSTransferor.py b/src/python/WMCore/MicroService/MSTransferor/MSTransferor.py
index 3446205bf..1036cd2bf 100644
--- a/src/python/WMCore/MicroService/MSTransferor/MSTransferor.py
+++ b/src/python/WMCore/MicroService/MSTransferor/MSTransferor.py
@@ -746,18 +746,21 @@ class MSTransferor(MSCore):
         """
         # Warn about data transfer subscriptions going above some threshold
         if aboveWarningThreshold:
-            alertName = "ms-transferor: Transfer over threshold: {}".format(transferId)
+            alertName = "{}: input data transfer over threshold: {}".format(self.alertServiceName,
+                                                                            wflowName)
             alertSeverity = "high"
             alertSummary = "[MS] Large pending data transfer under request id: {}".format(transferId)
-            alertDescription = "Workflow: {}\\nhas a large amount of ".format(wflowName)
-            alertDescription += "data subscribed: {} TB,\\n".format(teraBytes(dataSize))
+            alertDescription = "Workflow: {} has a large amount of ".format(wflowName)
+            alertDescription += "data subscribed: {} TB, ".format(teraBytes(dataSize))
             alertDescription += "for {} data: {}.""".format(dataIn['type'], dataIn['name'])
 
             try:
-                self.alertManagerApi.sendAlert(alertName, alertSeverity, alertSummary, alertDescription, self.alertServiceName)
+                # alert to expiry in an hour from now
+                self.alertManagerApi.sendAlert(alertName, alertSeverity, alertSummary, alertDescription,
+                                               self.alertServiceName, endSecs=1 * 60 * 60)
             except Exception as ex:
                 self.logger.exception("Failed to send alert to %s. Error: %s", self.alertManagerUrl, str(ex))
-            self.logger.info(alertDescription)
+            self.logger.warning(alertDescription)
 
     def _getValidSites(self, wflow, dataIn):
         """
['src/python/WMCore/MicroService/MSTransferor/MSTransferor.py']