Acceptance Tests: restore downloading of VM images

Acceptance Tests: restore downloading of VM images

The "get-vm-images" target defined in tests/Makefile.include is a
prerequisite for "check-acceptance", so that those files get
downloaded before the Avocado job even starts.

It looks like on c401c058a1c a TARGETS variable was introduced with a
different content than it was previously coming from the main
Makefile.  From that point on, the "get-vm-images" succeed without
doing anything because there was no matching architecture to download.

This restores the download of images (that match targets to be built)
before the job starts, eliminating downloads and their associated
failures during the tests.

Signed-off-by: Cleber Rosa <crosa@redhat.com>
Reviewed-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
Reviewed-by: Willian Rampazzo <willianr@redhat.com>
Message-Id: <20210225232122.1254879-2-crosa@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>