Revert "ucounts: Increase ucounts reference counter before the security hook"

This reverts commit b493af3a which is
commit bbb6d0f3 upstream.

The "original" commit 905ae01c

 ("Add a reference to ucounts for each
cred"), should not have been applied to the 5.10.y tree, so revert it,
and the follow-on fixup patches as well.

Reported-by: "Eric W. Biederman" <ebiederm@xmission.com>
Link: https://lore.kernel.org/r/87v93k4bl6.fsf@disp2133


Cc: Alexey Gladkov <legion@kernel.org>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>