chore: Replacing custom map util functions with golang std functions

[DaanV2]

Golang's standard library is growing with their own functions, which means we can start replacing them golangs functions.

NOTE: before removing the functions I use the removed unit tests, to test if golangs own function match the expected behavior.

Checklist:

• (c) this does not need to be in the release notes.
• The title of the PR states what changed and the related issues number (used for the release note).
• The title of the PR conforms to the Toolchain Guide
• I've included "Closes [ISSUE #]" or "Fixes [ISSUE #]" in the description to automatically close the associated issue.
• I've updated both the CLI and UI to expose my feature, or I plan to submit a second PR with them.
• I've updated documentation as required by this PR.
• I have signed off all my commits as required by DCO
• I have written unit and/or e2e tests for my change. PRs without these are unlikely to be merged.
• My build is green (troubleshooting builds).
• My new feature complies with the feature status guidelines.
• I have added a brief description of why this PR is necessary and/or what this PR solves.

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[codecov]

Codecov Report

Attention: Patch coverage is 63.63636% with 4 lines in your changes missing coverage. Please review.

Project coverage is 55.95%. Comparing base (cfa1c89) to head (afded8c).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
pkg/apis/application/v1alpha1/types.go	0.00%	2 Missing ⚠️
server/application/application.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #20311   +/-   ##
=======================================
  Coverage   55.95%   55.95%           
=======================================
  Files         322      322           
  Lines       44714    44704   -10     
=======================================
- Hits        25021    25016    -5     
+ Misses      17101    17100    -1     
+ Partials     2592     2588    -4     

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[crenshaw-dev]

lgtm, thanks!