v2020 ← v2021: lava: Fix common tests running out of storage on sdk

Backport of tests/apertis-test-cases!262 (merged)

See https://lava.collabora.co.uk/scheduler/job/3801267

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.