Check #reconnect_can_restore_state? once, before running block

The block can't affect reconnectability, because we'll be re-running it
anyway.

Also, only #reconnect! once per query, to avoid squaring the total
number of permitted retries while attempting to query a pathologically
flakey server.

Author: matthewd

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -867,11 +867,12 @@ def with_raw_connection(allow_retry: false, uses_transaction: true)
             materialize_transactions if uses_transaction
 
             retries_available = allow_retry ? connection_retries : 0
+            reconnectable = reconnect_can_restore_state?
 
             if @verified
               # Cool, we're confident the connection's ready to use. (Note this might have
               # become true during the above #materialize_transactions.)
-            elsif reconnect_can_restore_state?
+            elsif reconnectable
               if allow_retry
                 # Not sure about the connection yet, but if anything goes wrong we can
                 # just reconnect and re-run our query
@@ -899,9 +900,11 @@ def with_raw_connection(allow_retry: false, uses_transaction: true)
                 if retryable_query_error?(translated_exception)
                   backoff(connection_retries - retries_available)
                   retry
-                elsif retryable_connection_error?(translated_exception) &&
-                    reconnect_can_restore_state?
+                elsif reconnectable && retryable_connection_error?(translated_exception)
                   reconnect!(restore_transactions: true)
+                  # Only allowed to reconnect once, because reconnect! has its own retry
+                  # loop
+                  reconnectable = false
                   retry
                 end
               end