lava: Fix common tests running out of storage on sdk

The common tests group currently blows up on LAVA when submitted to
QEMU-based DUTs as we do for the SDK and base SDK images because the
dispatcher runs out of disk space while unpacking the overlay before
uploading it to the DUT:

    Job error: tar_in: tar subcommand failed on directory: /:
    tar: 0/tests/1_disk-rootfs-fsck/apertis-tests/.git/objects/pack/pack-c1d7de14a133c29fdcacfeef5eba98291ada6c91.pack:
    Wrote only 2048 of 10240 bytes tar: 0/tests/1_disk-rootfs-fsck/apertis-tests/.git/packed-refs:
    Cannot write: No space left on device

In particular this is because the git repositoriee installed by the
apparmor-gstreamer1.0 and gstreamer1.0-decode testcases used to ship a
large copy of the Big Buck Bunny movie. Even if the test file has been
dropped from the HEAD of both repositories in favor of the media sample
file for the same movie pre-installed on the images, LAVA fails because
it does not do a shallow checkout but it ends up putting the whole git
hisotry in the overlay.

To side-step the issue, move all the apparmor tests still in the
`common-standalone` group to the `apparmor-standalone` group, but keep
skipping them on minimal images.

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>