Test_bgpmon_V6 - T2 Update

[sresri2]

Description of PR

Summary:
Enable test_bgpmon_v6 on VS T2 multi-ASIC by fixing per-ASIC "Loopback4096" config lookup and removing the skip.

This test already uses multi-ASIC fixtures, but common_v6_setup_teardown fetched Loopback4096 config with functionality for a single frontend ASIC. On multi-ASIC, ASIC index 0 is falsy (in python), so the fixture used the wrong config path when ASIC 0 was selected.

Note: There is still a separate global skip relevant to this test, but that is unrelated to enabling this test on T2, so it is intentionally left unchanged.

Changes:

• Use get_asic_config_facts() for Loopback4096 lookup on the selected frontend ASIC.
• Remove the T2 conditional skip for this test.

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• New Test case
  • Skipped for non-supported platforms
• Test case improvement

Back port request

• 202311
• 202405
• 202411
• 202505
• 202511
• 202512
• 202605

Tracking issue/work item for backport/cherry-pick request (GitHub issue or Microsoft ADO):
Failure type:

Tested branch

• master
• 202311
• 202405
• 202411
• 202505
• 202511
• 202512
• 202605
• N/A

Test result

N/A

Approach

What is the motivation for this PR?

test_bgpmon_v6 configures a BGP monitor peer using Loopback4096 on the selected frontend ASIC. The setup reads config from the correct ASIC namespace on multi-ASIC T2 linecards. The previous check on enum_rand_one_frontend_asic_index failed when the selected ASIC was index 0.

How did you do it?

• Replaced the enum_one_frontend_asic branch with get_asic_config_facts.
• Removed the VS T2 skip from tests_mark_conditions_vs_t2.yaml.

How did you verify/test it?

• Code review for quality and functionality check.
• Code review for consistency with other multi-ASIC T2 Updates
• Full validation on GitHub checks / pipeline.

Any platform specific information?

N/A

Supported testbed topology if it's a new test case?

Existing test, logic for T2 Updated.

Documentation

N/A

[mssonicbld]

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[github-actions]

@StormLiangMS @wangxin @yxieca A user wants to merge changes to the conditional mark files into master. Please review.