s3: tests: Add regression test for bug 13992.

s3: tests: Add regression test for bug 13992.

Subtle extra test. Mark as knownfail for now.

'^ user1$' must appear MORE THAN ONCE, as it can read more than one
share. The previous test found user1, but only once as the bug only
allows reading the security descriptor for one share, and we were
unlucky that the first share security descriptor returned allows
user1 to read from it.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13992

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>