s3/smbd: add and use retry_open() instead of defer_open() in two places

s3/smbd: add and use retry_open() instead of defer_open() in two places

Add a new function that does an immediate open rescheduling.

The first deferred open this commit changes was never scheduled, as the
scheduling relies on a timeout of the watch on the sharemode lock.

This has been broken since the commits in

$ git log --reverse -p -10 8283fd0e0090ed12b0b12d5acb550642d621b026

That patchset added the dbwrap watch record logic to defer_open() and
removed the timers.

I'm doing this mainly to untangle the defer_open() logic which is
complicated by the lck arg.

Bug: https://bugzilla.samba.org/show_bug.cgi?id=7537

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>