s3/locking: update share_entry_stale_pid() check for Persistent Handles

s3/locking: update share_entry_stale_pid() check for Persistent Handles

Disconnected Persistent Handles are NOT "stale" and must be preserved. But while
we're at it to check if the handle is connected or not, remember this
information so we can check this later in the open code.

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Anoop C S <anoopcs@samba.org>