CSTACKEX-286: Add resize coverage for pool limits, VMs and zone scope

Extend the ONTAP pool lifecycle and zone-scoped suites with resize cases
that were previously untested.

Pool lifecycle (both NFS3 and iSCSI), now 15 tests:
  - test_03 rejects a grow past the 300 TiB ONTAP FlexVol maximum,
    asserting ONTAP's autosize-maximum error so an unrelated failure
    such as exhausted aggregate space cannot pass the test
  - test_12 deploys a VM and attaches the volume before the negative
    shrink, so the shrink is attempted against a volume in use
  - test_14 grows and shrinks the pool while the VM holds the volume,
    checking the VM stays running and keeps the volume across both
  - test_13 asserts ONTAP's "too small to hold the current volume data"
    wording rather than a broad keyword match

Zone-scoped pool (both protocols), now 6 tests:
  - test_02 and test_03 grow and safely shrink the pool, verifying the
    export policy (NFS3) and igroups (iSCSI) survive the resize

Shared VM discovery, teardown and volume helpers move to
OntapTestBase so both protocol suites reuse them, and a missing
enableStorageMaintenance import is added there.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: sp16743

test/integration/plugins/ontap/README.md

@@ -306,14 +306,14 @@ self.assertEqual(result.state, "Maintenance")
 
 | Suite | File | Tests | What it covers |
 |-------|------|-------|---------------|
-| NFS3 Pool Lifecycle | `nfs3/pool/test_pool_lifecycle.py` | 11 | Create, grow, safe shrink, disable, enable, maintenance, delete, then re-create with a volume, reject shrink below used capacity, cleanup |
+| NFS3 Pool Lifecycle | `nfs3/pool/test_pool_lifecycle.py` | 15 | Create, grow to 300 TiB, reject grow past 300 TiB, safe shrink, disable, enable, maintenance, resize in maintenance, delete, then re-create with a volume, reject shrink below used capacity, deploy a VM and attach the volume, cleanup |
 | NFS3 Pool with Volumes | `nfs3/pool/test_pool_with_volumes.py` | 7 | Same + live volume present; negative delete guard |
-| NFS3 Zone-Scoped Pool | `nfs3/pool/test_zone_scoped_pool.py` | 4 | Zone scope — all hosts connected via `attachZone` |
+| NFS3 Zone-Scoped Pool | `nfs3/pool/test_zone_scoped_pool.py` | 6 | Zone scope — all hosts connected via `attachZone`; grow and safe shrink |
 | NFS3 Volume Lifecycle | `nfs3/volume/test_volume_lifecycle.py` | 5 | Volume is metadata-only; FlexVol unchanged on delete |
 | NFS3 VM + Volume Attach | `nfs3/instance/test_vm_volume_attach.py` | 8 | Full VM lifecycle with hot-plug/detach |
-| iSCSI Pool Lifecycle | `iscsi/pool/test_pool_lifecycle.py` | 11 | Create, grow, safe shrink, disable, enable, maintenance, delete + igroups, then re-create with a volume (LUN), reject shrink below used capacity, cleanup |
+| iSCSI Pool Lifecycle | `iscsi/pool/test_pool_lifecycle.py` | 15 | Create, grow to 300 TiB, reject grow past 300 TiB, safe shrink, disable, enable, maintenance, resize in maintenance, delete + igroups, then re-create with a volume (LUN), reject shrink below used capacity, deploy a VM and attach the volume, cleanup |
 | iSCSI Pool with Volumes | `iscsi/pool/test_pool_with_volumes.py` | 7 | Same + live LUN present; negative delete guard |
-| iSCSI Zone-Scoped Pool | `iscsi/pool/test_zone_scoped_pool.py` | 4 | Zone scope |
+| iSCSI Zone-Scoped Pool | `iscsi/pool/test_zone_scoped_pool.py` | 6 | Zone scope; grow and safe shrink |
 | iSCSI Volume Lifecycle | `iscsi/volume/test_volume_lifecycle.py` | 5 | LUN created per CS volume; LUN removed on delete |
 | iSCSI VM + Volume Attach | `iscsi/instance/test_vm_volume_attach.py` | 8 | Full VM lifecycle; LUN-maps on VM start/stop/detach |