chore(kuma-cp) check explicit service account name

[jakubdyszkiewicz]

Summary

When checking if we can modify resources on Zone CP we were checking just a namespace of service account.
We should check an explicit name of a service account that is used to run Kuma CP, so it's more secure.

Issues resolved

No reported issues.

Documentation

• No docs, internal changes only.

Testing

• Unit tests
• E2E tests
• Manual testing on Universal
• Manual testing on Kubernetes

Backwards compatibility

• Add backport-to-stable label if the code is backwards compatible. Otherwise, list breaking changes.

[codecov-commenter]

Codecov Report

Merging #3228 (a3a8808) into master (8620ed0) will decrease coverage by 0.00%.
The diff coverage is 88.88%.

@@            Coverage Diff             @@
##           master    #3228      +/-   ##
==========================================
- Coverage   52.40%   52.40%   -0.01%     
==========================================
  Files         928      928              
  Lines       54044    54040       -4     
==========================================
- Hits        28321    28317       -4     
- Misses      23502    23503       +1     
+ Partials     2221     2220       -1     

Impacted Files	Coverage Δ
pkg/plugins/runtime/k8s/plugin.go	1.12% <0.00%> (ø)
pkg/config/plugins/runtime/k8s/config.go	86.39% <100.00%> (+0.08%)	⬆️
pkg/plugins/runtime/k8s/webhooks/validation.go	87.28% <100.00%> (-0.52%)	⬇️
pkg/plugins/runtime/gateway/route/sorter.go	61.53% <0.00%> (-10.26%)	⬇️
api/observability/v1/mads.pb.go	35.56% <0.00%> (+1.03%)	⬆️
pkg/mads/v1/client/client.go	43.75% <0.00%> (+2.50%)	⬆️

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