feat: validate atm profile when handling backend update

[zhiying-lin]

What type of PR is this?

/kind feature

What this PR does / why we need it:

validate whether the atm profile and populate the backend status

Which issue(s) this PR fixes:

Fixes #

Requirements:

• run make reviewable for basic local test
• Read and followed fleet-networking's Code of conduct.
• uses conventional commit messages
• includes documentation
• adds unit tests

How has this code been tested

Special notes for your reviewer

[codecov]

Codecov Report

Attention: Patch coverage is 91.66667% with 3 lines in your changes missing coverage. Please review.

Project coverage is 78.83%. Comparing base (728dd0d) to head (c96852a).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...ontrollers/hub/trafficmanagerbackend/controller.go	91.66%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #208      +/-   ##
==========================================
+ Coverage   78.42%   78.83%   +0.41%     
==========================================
  Files          27       27              
  Lines        3504     3539      +35     
==========================================
+ Hits         2748     2790      +42     
+ Misses        604      600       -4     
+ Partials      152      149       -3     

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