OF-1692: Broadcast original 'unavailable' stanza when leaving MUC. When a client sends a presence 'unavailable' stanza to leave a multi-user chat room, Openfire broadcasts not that stanza, but one that was received earlier (and is modified to include 'unavailable').
This appears to be an oversight, combined with a better-safe-than-sorry override of the presence type.
Openfire should broadcast the original stanza (modified to add some metadata where needed). This will, for instance, keep intact the reflected stanza ID.
OF-1691: XEP-0133's "Delete User" should use jid-multi https://xmpp.org/extensions/xep-0133.html#delete-user describes an ad-hoc command that is used to delete users. Our old implementation allows for just one user to be deleted, while the XEP defines that multiple JIDs should be allowed.
