Option to suppress resource exceeded alerting (#6173)

The expected use case is to suppress MAU limiting on small instances

synapse/config/server.py

@@ -171,6 +171,7 @@ class ServerConfig(Config):
         )
 
         self.mau_trial_days = config.get("mau_trial_days", 0)
+        self.mau_limit_alerting = config.get("mau_limit_alerting", True)
 
         # How long to keep redacted events in the database in unredacted form
         # before redacting them.
@@ -192,7 +193,6 @@ class ServerConfig(Config):
         # Options to disable HS
         self.hs_disabled = config.get("hs_disabled", False)
         self.hs_disabled_message = config.get("hs_disabled_message", "")
-        self.hs_disabled_limit_type = config.get("hs_disabled_limit_type", "")
 
         # Admin uri to direct users at should their instance become blocked
         # due to resource constraints
@@ -675,7 +675,6 @@ class ServerConfig(Config):
         #
         #hs_disabled: false
         #hs_disabled_message: 'Human readable reason for why the HS is blocked'
-        #hs_disabled_limit_type: 'error code(str), to help clients decode reason'
 
         # Monthly Active User Blocking
         #
@@ -695,9 +694,16 @@ class ServerConfig(Config):
         # sign up in a short space of time never to return after their initial
         # session.
         #
+        # 'mau_limit_alerting' is a means of limiting client side alerting
+        # should the mau limit be reached. This is useful for small instances
+        # where the admin has 5 mau seats (say) for 5 specific people and no
+        # interest increasing the mau limit further. Defaults to True, which
+        # means that alerting is enabled
+        #
         #limit_usage_by_mau: false
         #max_mau_value: 50
         #mau_trial_days: 2
+        #mau_limit_alerting: false
 
         # If enabled, the metrics for the number of monthly active users will
         # be populated, however no one will be limited. If limit_usage_by_mau