lib/message-property: sync removed properties to the database

_notmuch_message_remove_all_properties wasn't syncing the message back
to the database but was still invalidating the metadata, giving the
impression the properties had actually been removed.

Also move the metadata invalidation to _notmuch_message_remove_terms
to be closer to what's done in _notmuch_message_modify_property and
_notmuch_message_remove_term.