skip test_gnoi_system_reboot_warm for isolated topo

[sdszhang]

Description of PR

Summary:
Skip warm reboot for isolated topo.

Fix the following error which will occur if any case run after test_gnoi_system_reboot_warm:

>               pt_assert(False, failure_message)
E               Failed: Got matched syslog in processes "analyze_logs--<MultiAsicSonicHost xxxxxx>" exit code:"1"
E               match: 1
E               expected_match: 0
E               expected_missing_match: 0
E               
E               Match Messages:
E               2025 Nov 15 20:24:24.385401 xxxxx ERR sysmgr#sysmgr#rebootbackend: :- log_error_and_set_non_retry_failure: failed to warm reboot

Type of change

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

Back port request

• 202205
• 202305
• 202311
• 202405
• 202411
• 202505

Approach

What is the motivation for this PR?

skip warm reboot for isolated topo as it's not needed.

How did you do it?

How did you verify/test it?

Any platform specific information?

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

Documentation

[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[Janetxxx]

LGTM

[r12f]

lgtm. approved.