[improvement] : simplify rate limits as we now have only one limit for POST calls

[rahulait]

What this PR does / why we need it:

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged): Fixes #

Special notes for your reviewer:

TODOs:

• [ ] squashed commits
• [ ] includes documentation
• [ ] adds unit tests
• [ ] adds or updates e2e tests

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 64.91%. Comparing base (1c49829) to head (4a6665d). Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
controller/linodemachine_controller_helpers.go	66.66%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #540      +/-   ##
==========================================
- Coverage   64.93%   64.91%   -0.02%     
==========================================
  Files          79       79              
  Lines        4309     4298      -11     
==========================================
- Hits         2798     2790       -8     
+ Misses       1242     1239       -3     
  Partials      269      269              

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