Move volume mount group feature GA

[gnufied]

Drop alpha from volume_mount_group feature.

[jdef]

is this the first time we've promoted something from alpha to GA? i'm wondering if there's a compatibility impact w/ respect to completely dropping the alpha annotations vs. setting them to false. maybe i'm overthinking this. has anyone tested interactions between older bindings (w/ alpha set) against newer bindings (w/o alpha)?

[gnufied]

This is another instance #499 when we moved things over from alpha to GA. I will look into compatibility aspects of when we move a feature from alpha to GA.

[gnufied]

@jdef So I ran e2e of k8s by updating kubernetes with my version of CSI driver and let driver run a released version of CSI with alpha APIs. And all e2es are still passing:

  should pass FSGroup to CSI driver if it is set in pod and driver supports VOLUME_MOUNT_GROUP                                                                                                                                                               
    should not pass FSGroup to CSI driver if it is set in pod and driver does not supports VOLUME_MOUNT_GROUP                                                                                                                                                         

Is that enough as signal that dropping alpha annotation does not break anything?

[jingxu97]

/cc @saad-ali

[jdef]

LGTM