DO NOT MERGE: Test GatewayAPI v1.4.0-rc2

[ciarams87]

Proposed changes

Problem: We need to test the latest rc tag of the 1.4.0 Gateway API release, ensure the conformance tests pass and provide feedback if we see any issues

Solution: Upgrade to the v1.4.0-rc2 tag, make all the necessary changes to support the latest API, and run the conformance tests. Also enable the BackendTLSPolicy tests.

Testing: Ran the conformance tests

Closes #ISSUE

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

If this PR introduces a change that affects users and needs to be mentioned in the release notes,
please add a brief note that summarizes the change.

[codecov]

Codecov Report

❌ Patch coverage is 78.18182% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.89%. Comparing base (cf38a6f) to head (5c0f69d).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/controller/state/conditions/conditions.go	0.00%	12 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3982      +/-   ##
==========================================
+ Coverage   86.84%   86.89%   +0.04%     
==========================================
  Files         128      128              
  Lines       16607    16602       -5     
  Branches       62       62              
==========================================
+ Hits        14423    14426       +3     
+ Misses       2003     1994       -9     
- Partials      181      182       +1     

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