gc: remove unused launchctl_get_uid() call

gc: remove unused launchctl_get_uid() call

When the launchctl_boot_plist() function was added in
a16eb6b1ff3 (maintenance: skip bootout/bootstrap when plist is
registered, 2021-08-24), an unused call to launchctl_get_uid() was
added along with it. That call appears to have been copy/pasted from
launchctl_boot_plist().

Since we can remove that, we can also get rid of the "result"
variable, whose only purpose was allow for the free() between its
assignment and the return. That pattern also appears to have been
copy/pasted from launchctl_boot_plist().

As the patch shows the returned value from launchctl_get_uid() wasn't
used at all in this function. The launchctl_get_uid() function itself
just calls xstrfmt() and getuid(), neither of which have any subtle
global side-effects, so this removal is safe.

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