gitweb: remove "test" and "test-installed" targets

gitweb: remove "test" and "test-installed" targets

Remove the special "test" targets for gitweb added in
958a8467216 (gitweb/Makefile: Add 'test' and 'test-installed' targets,
2010-09-26). Unlike e.g. "contrib/scalar" and "contrib/subtree" the
"gitweb" tests themselves live in our top-level t/ directory.

It therefore doesn't make sense to maintain this indirection, no more
than it would to have a "git-send-email-test". By dropping it we'll
also free other tests to use the t95*.sh prefix.

These removed targets are unlikely to be used by anyone, and to the
extent that they are we can easily use an invocation like this
instead:

	make test T='t[0-9]*gitweb*.sh'

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
Signed-off-by: Junio C Hamano <redacted>