use annotations to set QOS for DATA PVC

[boddumanohar]

PR simplyblock/simplyblock-csi#294 introduces setting IOPS values using annotations.

simplybk/qos-rw-iops: "1000"

This will essentially remove the need for having to create a storage class. The storage class serves two purposes: IOPS via qos_rw_iops in CSI parameters, and it's also the storageClassName reference on every PVC (data, WAL, autoscaler, db, storage). If we migrate to annotations, we'd use the base SIMPLYBLOCK_CSI_STORAGE_CLASS directly and drop the per-branch storage class entirely.

But with this approach when a branch is cloned/restored it will use the SIMPLYBLOCK_CSI_STORAGE_CLASS storage class which doesn't have IOPS QOS set. So we need to explicitly call update_branch_volume_iops as a second step.

Test cases:

• create a new branch should have IOPS set correctly
• Resize IOPS should should work correctly
• Branch clone with the default values should inherit the IOPS from the parent branch
• Branch restore with default parameters should inherit IOPS from the parent branch
• Branch clone/branch restore with override IOPS should work correctly