Ensure we don't lose values on edit of cluster scan resources

[nwmac]

Summary

Fixes #12411

Note: #12412 is required to fix the specific issue on that field.

Occurred changes and/or fixed issues

We were previously clearing out the spec of the resource on edit. Don't know why.

This PR updates that so that we preserve the data in the resource on edit

Areas or cases that should be tested

Test as per the issue above.

Due to time constraints, this will need manual testing.

Checklist

• The PR is linked to an issue and the linked issue has a Milestone, or no issue is needed
• The PR has a Milestone
• The PR template has been filled out
• The PR has been self reviewed
• The PR has a reviewer assigned
• The PR has automated tests or clear instructions for manual tests and the linked issue has appropriate QA labels, or tests are not needed
• The PR has reviewed with UX and tested in light and dark mode, or there are no UX changes

[aalves08]

Gave it a go and LGTM @nwmac