fix(vpp): backport VLAN member punt support to 202605

[auspham]

Description of PR

Summary:
Conflict-resolved backport of #1981 to the 202605 branch. This preserves VLAN member-interface punt support for ARP, LLDP, LACP, and DHCP while adapting the changes to the older branch's VPP API registration and sub-port implementations.

Fixes # (not applicable - backport of #1981)

Type of change

• Bug fix
• New feature
• Refactor / cleanup
• Documentation update
• Test improvement

Approach

What is the motivation for this PR?

The 202605 VPP virtual-switch branch needs the control-plane punt behavior introduced by #1981 for tagged and untagged VLAN members.

Work item tracking

• Microsoft ADO (number only): N/A

How did you do it?

Resolved the cherry-pick conflicts semantically against 202605. The backport keeps the branch's existing API handler layout and interface mapping, adds only the classify and vlib registrations required by #1981, preserves the branch's existing refresh behavior for sub-port router interfaces, and excludes unrelated newer-master sFlow, BFD TOS, bridge tracking, and LAG changes.

How did you verify/test it?

• Ran git diff --check HEAD^ HEAD.
• Confirmed no conflict markers remain in the changed files.
• Reviewed the final five-file delta against source commit cfe265dece50de9b98d3cc57b4e76316f3683c9d and origin/202605.
• A local VPP compile was not available because this host lacks the required VPP development headers and autotools; no dependencies were added.

Any platform specific information?

This change is specific to the VPP virtual-switch implementation under vslib/vpp.

Documentation

No documentation changes are required for this branch backport.

[mssonicbld]

/azp run

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[auspham]

202605 functional validation:

• Current 202605 t0-vpp runs fail test_dhcp_relay_default[isc-relay-agent] because no relayed DHCPDISCOVER packets reach the four server-facing ports (0 != 4).
• A 202605 validation image combined sonic-sairedis vpp: support punting ARP, LLDP, LACP, DHCP via member interface in VLAN (re-opened) #1981 with sonic-platform-vpp [bug]: do not translate SAI_NULL_OBJECT_ID in saiplayer #257 and Add Nephos ASIC #271: sonic-buildimage PR [validation][202605] VPP PortChannel punt for DHCP relay sonic-buildimage#29067 at 2e297e93668c2a791fba6a590befa8eb15bb5ca9, Azure build 1196355.
• Elastictest https://elastictest.org/scheduler/testplan/6a84bdd4e437251d82f52a1a ran public sonic-mgmt 202605 on t0-vpp. dhcp_relay/test_dhcp_relay.py passed with 14 passed and 2 expected skips, including test_dhcp_relay_default[isc-relay-agent]; pretest and posttest also passed.
• The backported DHCP classify/punt block in SwitchVppFdb.cpp is identical to the validated vpp: support punting ARP, LLDP, LACP, DHCP via member interface in VLAN (re-opened) #1981 merge. The conflict resolution preserves only 202605 branch-specific surrounding APIs and excludes unrelated master changes.

[lolyu]

Hi @auspham, we don't need to backport vpp changes into 202605

[yue-fred-gao]

Hi @auspham, we don't need to backport vpp changes into 202605

agreed. If t0-vpp is enabled in 202605, we should disable it.