fix(muc): do not rejoin rooms on stream:management:resumed
fix(muc): do not rejoin rooms on stream:management:resumed

There's no need to rejoin any already joined MUC rooms upon
session resume, because the user should still be inside those rooms.
That's entire reason for doing SM resume - to avoid having to rebuild
the session's state when connection drops.

otalk/stanza.io,legastero/stanza.io,legastero/stanza.io,otalk/stanza.io