fix: wrap error when nodepool update/delete fails

[salasberryfin]

/kind bug

What this PR does / why we need it:

Controller logs show an error during reconciliation if GCP-controlled automatic updates are currently running on node pools. This is because the error received from Google's API cannot be unwrapped, even if there is logic in the controller code to check for this failure. Same behavior occurs when deleting a cluster but, in this case, there's no existing logic to handle this API response.

This PR returns the error in an unwrappable format for update operations and adds the same error validation for deletions.

Which issue(s) this PR fixes:
Fixes #1363

Special notes for your reviewer:

TODOs:

• squashed commits
• includes documentation
• adds unit tests

Release note:

Fix controller error on GKE node pool updates

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[richardcase]

/approve

[cpanato]

Thanks

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cpanato, richardcase, salasberryfin

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[salasberryfin]

/cherrypick release-1.8

[k8s-infra-cherrypick-robot]

@salasberryfin: new pull request created: #1395

In response to this:

/cherrypick release-1.8

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