rm failing preStop hook

[AndreasBurger]

How to categorize this PR?
/area storage
/kind bug
/platform openstack

What this PR does / why we need it:
This PR removes the failing preStop lifecycle hook from the node-driver-registrar container in csi-driver-node daemonset.yaml. The distroless registrar image lacks /bin/sh, causing the hook to fail. Socket removal is now handled internally by the registrar, eliminating the need for the hook (see kubernetes-csi/node-driver-registrar#61).

Special notes for your reviewer:
This is gardener/gardener-extension-provider-gcp#792 for Openstack

Release note:

Removed unnecessary preStop hook from `node-driver-registrar` in `csi-driver-node`, as socket removal is now handled internally by `node-driver-registrar`, resolving distroless image error.