Clarify log message

The host may have come back online or it is **still** online after a
replica status check.

ee/lib/gitlab/database/load_balancing/host.rb

@@ -74,7 +74,7 @@ module Gitlab
           if @online
             LoadBalancing::Logger.info(
               event: :host_online,
-              message: 'Host came back online',
+              message: 'Host is online after replica status check',
               db_host: @host,
               db_port: @port
             )