Fix flake | Enforcing a worker machineset to the NSG reconcile test

[ehvs]

NSG Flake|

Error eg:

ARO Operator - Azure Subnet Reconciler [It] must reconcile list of subnets when NSG is changed
/app/test/e2e/operator.go:377

  [FAILED] Timed out after 300.004s.
  The function passed to Eventually failed at /app/test/e2e/operator.go:423 with:
  Expected
      <map[string]string | len:0>: nil
  to satisfy predicate
      <func(map[string]string) bool>: 0x4689a40
  In [It] at: /app/test/e2e/operator.go:424 @ 12/12/25 09:07:49.164

  There were additional failures detected.  To

Test plan for issue:

• e2e