integration/plugin: remove deprecated overlay2.override_kernel_check
integration/plugin: remove deprecated overlay2.override_kernel_check

It's no longer used since e226aea280efdc18f887e853b5eefd763b602937

Signed-off-by: Sebastiaan van Stijn <64b2b6d12bfe4baae7dad3d018f8cbf6b0e7a044@gone.nl>

jimjag/docker,jimjag/docker,moby/moby,Ramzec/docker,konstruktoid/docker-upstream,Mokolea/docker,trebonian/docker,trebonian/docker,Ramzec/docker,moby/moby,Ramzec/docker,Mokolea/docker,moby/moby,konstruktoid/docker-upstream,thaJeztah/docker,mahak/docker,mahak/docker,thaJeztah/docker,mahak/docker,Mokolea/docker,thaJeztah/docker,konstruktoid/docker-upstream,trebonian/docker,jimjag/docker,konstruktoid/docker-upstream,jimjag/docker,mahak/docker,moby/moby,thaJeztah/docker,Mokolea/docker,Ramzec/docker,trebonian/docker