git-tag: fix -l switch handling regression.

git-tag: fix -l switch handling regression.

The command itself takes an optional <pattern> argument that
limits the shown tags to the ones that match when in listing
mode that is triggered with '-l' option.  The <pattern> is not
an optional option-argument to '-l'.

With this fix, "git tag -l -n 4 v0.99" works as expected.

It also removes a few bogus tests in t7004.

Signed-off-by: Pierre Habouzit <madcoder@debian.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>