Do various cleanups once we have bootc v1.6.0

[jlebon]

See #4274 (comment).

[jlebon]

bootc-1.6.0-1.fc44 is in rawhide now. I've tagged bootc-1.6.0-1.fc42 into the continuous tag, so it should be in the next cosa build.

[PeaceRebel]

#4285 (comment)

This issue still exist in bootc.