[cinder-csi-plugin] Volume context is not used

[stephenfin]

/kind bug

What happened:

Spotted while working on https://github.com/kubernetes/cloud-provider-openstack/issues/2861.

We generate a volCtx map and pass this to the getCreateVolumeResponse helper, as seen here. However, we never use this and instead use a different volCnx variable, as seen here. This looks like a trivial mistake in #2687.

What you expected to happen:

n/a

How to reproduce it:

n/a

Anything else we need to know?:

n/a

Environment:

• openstack-cloud-controller-manager(or other related binary) version: master
• OpenStack version: n/a
• Others: n/a