Fix issues with failing acceptance tests

[kolsean]

We often get following errors in the CI acceptance test suite:

--- FAIL: TestAccMKSNodegroupV1Basic (596.04s)
13    testing_new.go:22: WARNING: destroy failed, so remote objects may still exist and be subject to billing
14    testing_new.go:22: failed to destroy: terraform failed: exit status 1
15        
16        stderr:
17        
18        Error: error deleting nodegroup 'e3b87082-9265-416c-ba6c-18d0fb951f08/7f67eae2-85c5-4eb8-9a10-25d2804829c8': mks-go: got the 409 status code from the server: {"error":{"message":"Can't perform the operation on the cluster in MAINTENANCE status"}}
19