.gitlab-ci.d/cirrus.yml: Shorten the runtime of the macOS and FreeBSD jobs

.gitlab-ci.d/cirrus.yml: Shorten the runtime of the macOS and FreeBSD jobs

Cirrus-CI introduced limitations to the free CI minutes. To avoid that
we are consuming them too fast, let's drop the usual targets that are
not that important since they are either a subset of another target
(like i386 or ppc being a subset of x86_64 or ppc64 respectively), or
since there is still a similar target with the opposite endianness
(like xtensa/xtensael, microblaze/microblazeel etc.).

Message-ID: <20240429100113.53357-1-thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>