Deleting An Email Channel Should Remove All Orphaned Emails

Issue Summary

If a user deletes an email channel in JIRA and creates a new one, JIRA should delete all references to this email channel in the database. Especially in the MailConnection table and the MailItem table as if there are emails that failed originally, when you remove the email channel, JIRA Service Desk should not persist these emails in the database.

Expected Behavior

Have JIRA Service Desk remove all mails related to this mailchannel with the old id once the channel is removed or set a new Status other than the ones used by by working mail channels.

Existing Behavior

JIRA would leave all data related to the mail channel that were in the process of being processed the way they were making it difficult to identify without knowing the purged ID and also, it would never process the emails anymore hence there is no reason to actually persist the data from these mail servers.