Enhancement: Regression test for mgmtd config loading issue

[Bojun-Feng]

Is it platform specific

generic

Importance or Severity

Medium

Description of the enhancement

A fix was merged in FRR for config missing issue.

Issue: #21931 #18541
Fix (merged): #18601

We need to coordinate test coverage to prevent regression.

This issue was also raised in the sonic-mgmt Repo: sonic-net/sonic-mgmt#21342

Current Behavior

There is no test to catch regressions.

Proposed Behavior

We should have a regression test.

[Bojun-Feng]

I have a PR proposed last week. Passes all tests and waiting for review.

Please assign me to the issue.