Defer MessagingGroup#recycle until bind completes

There is a "race condition" where a MessagingGroup is recycled while the
contents of that group are being used elsewhere in the
ConversationLayout, namely in the "image message container" used to show
the most recent image message in the collapsed state.

This state isn't cleared until later in the bind() process, which
unfortunately depends on the groups being updated. For that reason, we
defer all synchronous calls to recycle() until the end of bind(), which
will ensure that the old groups are still around as long as necessary.

Fixes: 212689920
Test: manual
Change-Id: Idef815d54690544615512bd2bd1006f172403e18