Fix unchecked type assertions

[lucacome]

Proposed changes

Fixes the remaining unchecked type assertions

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

Release notes

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please add a brief note that summarizes the change.

NONE

[kate-osborn]

We have a helper function that we use for type assertions: https://github.com/nginxinc/nginx-gateway-fabric/blob/9971881bf2a8afb746a0105e365ed71d4f8724df/internal/framework/helpers/helpers.go#L49C6-L49C20

[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 10 lines in your changes missing coverage. Please review.

Project coverage is 89.20%. Comparing base (dc3a925) to head (ee2070b).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/mode/static/manager.go	0.00%	8 Missing ⚠️
internal/framework/status/updater.go	50.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2580      +/-   ##
==========================================
- Coverage   95.19%   89.20%   -6.00%     
==========================================
  Files           1      100      +99     
  Lines         229     7642    +7413     
  Branches       50       50              
==========================================
+ Hits          218     6817    +6599     
- Misses         11      768     +757     
- Partials        0       57      +57     

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[salonichf5]

looks good except for the missing unit tests