refactor: remove engine pkg custom script unnecessary functions

[CecileRobertMichon]

Reason for Change:

Removes lines of code. Custom data no longer uses GetKubernetesB64 functions anymore so they do not need to be exported now that they are only used by the engine package.

Issue Fixed:

Requirements:

• uses conventional commit messages
• includes documentation
• adds unit tests
• tested upgrade from previous version

Notes:

[jackfrancis]

lgtm

[codecov]

Codecov Report

Merging #1036 into master will increase coverage by 0.07%.
The diff coverage is 95.65%.

@@            Coverage Diff             @@
##           master    #1036      +/-   ##
==========================================
+ Coverage   74.53%   74.61%   +0.07%     
==========================================
  Files         131      130       -1     
  Lines       17973    17897      -76     
==========================================
- Hits        13397    13353      -44     
+ Misses       3827     3795      -32     
  Partials      749      749

[jackfrancis]

/lgtm

[acs-bot]

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