[tests]: Remove mirror destination route correctly

[Xichen96]

What I did

Corrected test_MirrorDestMoveVlan cleanup to remove port_ip_prefix, the static route installed by the test, instead of attempting to remove the unrelated VLAN interface prefix.

Why I did it

The stale route keeps the Ethernet32 router interface referenced after the IPv4 case. The following IPv6 case can then inherit stale mirror-session state or fail interface recreation, especially when removal retry fencing is enabled.

How I verified it

PR CI only. The existing test covers both IPv4 and IPv6 paths and now removes the exact prefix each path installs.

Details if related

Observed while investigating repeated test_MirrorDestMoveVlan failures in #4746. This cleanup defect predates and is separate from that product change.

Work item tracking

• Microsoft ADO (number only): 39058195

[mssonicbld]

/azp run

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[Copilot]

Pull request overview

This PR fixes cleanup in the test_MirrorDestMoveVlan test so it deletes the exact static route the test installs (port_ip_prefix) rather than attempting to delete the VLAN interface’s connected prefix (vlan_intf_addr). This prevents stale route state from keeping the Ethernet32 router interface referenced across the IPv4→IPv6 subtest sequence.

Changes:

• Update test_MirrorDestMoveVlan teardown to call remove_route(dvs, port_ip_prefix) (matching the earlier add_route(dvs, port_ip_prefix, ...)).

[Xichen96]

Retrying CI once: build 1173115 ASAN compile hit the 60-minute agent limit, and regular vstest failed before pytest when host preflight sudo ip link del Vrf1 segfaulted (exit 139) on agent sonictest002E9A.

[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines:
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[Xichen96]

/azpw run

[mssonicbld]

⚠️ Notice: /azpw run only runs failed jobs now. If you want to trigger a whole pipline run, please rebase your branch or close and reopen the PR.
💡 Tip: You can also use /azpw retry to retry failed jobs directly.

Retrying failed(or canceled) jobs...

[mssonicbld]

Retrying failed(or canceled) stages in build 1173264:

✅Stage TestAsan:

• Job vstest: retried.

✅Stage Test:

• Job vstest: retried.
• Job vstest: retried.