fix: rateLimitDeployment ignoring pod labels and annotation merge

[oscarboher]

What type of PR is this?
fix
What this PR does / why we need it:
rateLimitDeployment.pod.labels where not applying to rate limit pods.
prometheus annotations where ignored if rateLimitDeployment.pod.annotations was defined

Which issue(s) this PR fixes:
Fixes #4226

[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 2 lines in your changes missing coverage. Please review.

Project coverage is 65.69%. Comparing base (4b8c2f5) to head (1eb1c07).
Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
...tructure/kubernetes/ratelimit/resource_provider.go	85.71%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4228   +/-   ##
=======================================
  Coverage   65.69%   65.69%           
=======================================
  Files         200      200           
  Lines       24095    24101    +6     
=======================================
+ Hits        15829    15833    +4     
- Misses       7134     7135    +1     
- Partials     1132     1133    +1     

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[arkodg]

can L195 be removed ? since L192 is already setting it

[oscarboher]

So maps.Copy(dest, src) overwrites keys existing in both maps with the src value. I want to make sure noone can override one of the selector labels from the rateLimitLabels, so I'm doing the last maps.Copy to overwrite with the selector labels in case someone added one of those labels in their values.

Also the destination map must not be nil so I cannot do something like:

podLabels := r.rateLimitDeployment.Pod.Labels
maps.Copy(podLabels, rateLimitLabels())

as it will fail if no pod labels are provided.
It looks a bit funny, I just didn't want to implement a function that merges two maps, but maybe it's worth it for clarity's sake. Let me know if you think so.

[arkodg]

ah thats a good way to ensure the labels can't be overridden
nit: this as a code comment would be helpful so the next dev gets the "why"

[arkodg]

LGTM thanks !

[arkodg]

LGTM thanks !