Made EchoNotificationDeleteJob flush transactions so the slave wait works
Made EchoNotificationDeleteJob flush transactions so the slave wait works

Change-Id: I18df9b973365cbcd7ef7f1abb816c31d0f5e2212

wikimedia/mediawiki-extensions-Echo,wikimedia/mediawiki-extensions-Echo,wikimedia/mediawiki-extensions-Echo,wikimedia/mediawiki-extensions-Echo