Use server side apply for NGF CRDs

[bjee19]

Proposed changes

Update docs and Makefile to use kubectl server side apply for NGF CRDs.

Problem: The NginxProxy CRD is getting too large for the normal client side kubectl apply to handle.

Solution: Update docs and Makefile to use kubectl server side apply for NGF CRDs.

Testing: Deployed NGF through manifests using server-side applied CRDs and manually ran through the policy examples and the cafe-example to make sure NGF still works.

Closes #3549

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.

Switch to recommending using kubectl server-side apply for Nginx Gateway Fabric CRDs. 

[bjee19]

Should note that with Helm, it does not run into the same client side apply issues as kubectl does so if a user were to deploy/install the CRDs with Helm there is no issue. Though if that same user wanted to update the CRDs after installation through Helm, they would be required to use kubectl apply and thus would run into the issue.

[bjee19]

This also means that all of our Functional tests and NFR tests that deploy NGF through Helm do not install the NGF CRDs through SSA, meaning NGF doesn't thoroughly test cases where the CRDs are SSA'd.

I could foresee unknown errors occurring with users who SSA their CRDs as it seems like there are some logic and validation differences between SSA and CSA. However, some of those issues were from a few years ago when SSA wasn't as popular and widely adopted, so maybe most of the issues have been hammered out.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.85%. Comparing base (75bde7c) to head (9f2a25a).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3589   +/-   ##
=======================================
  Coverage   86.85%   86.85%           
=======================================
  Files         127      127           
  Lines       15266    15266           
  Branches       62       62           
=======================================
+ Hits        13259    13260    +1     
+ Misses       1853     1851    -2     
- Partials      154      155    +1     

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