[manila-csi-plugin] Wait for access rule to become active after granting

[gouthampacha]

What this PR does / why we need it:

Manila's GrantAccess API is asynchronous — the access rule starts in queued_to_apply state and transitions through applying before reaching active. Both the NFS and CephFS share adapters were proceeding to mount immediately after granting access, which could fail if the backend hadn't applied the rule yet.

This PR adds a shared waitForAccessRuleActive helper that polls until the access rule reaches active state. On error state or timeout, the helper revokes the failed rule so the next reconcile retries cleanly. Both adapters now call this helper after GrantAccess.

For CephFS, this replaces the previous wait loop that only checked for AccessKey population without verifying the rule state. Waiting for active state implicitly guarantees the key is populated since Manila assigns the cephx key as part of applying the rule.

Which issue this PR fixes(if applicable):
fixes #3000

Special notes for reviewers:

Tested on a DevStack with both LVM (NFS) and native CephFS backends. Both protocols show the queued_to_apply → active transition, confirming the race window this fixes.

Release note:

[manila-csi-plugin] Wait for access rule to become active after granting access, fixing mount failures when backends are slow to apply rules.

[k8s-ci-robot]

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[kubernetes-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign stephenfin for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment