tests: don't lose exit status with "test <op> $(git ...)"

tests: don't lose exit status with "test <op> $(git ...)"

As with the preceding commit, rewrite tests that ran "git" inside
command substitution and lost the exit status of "git" so that we
notice the failing "git". This time around we're converting cases that
didn't involve a containing sub-shell around the command substitution.

In the case of "t0060-path-utils.sh" and
"t2005-checkout-index-symlinks.sh" convert the relevant code to using
the modern style of indentation and newline wrapping while having to
change it.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>