Add tests in flytepropeller/pkg /controller/executors from 72.3% to 87.3% coverage

[Future-Outlier]

Tracking issue

Fixes #4209
#4273

Describe your changes

Add tests in flytepropeller/pkg /controller/executors to leverage coverage.

• flytepropeller/pkg/controller/executors/execution_context_test.go
• flytepropeller/pkg/controller/executors/kube_test.go
• flytepropeller/pkg/controller/executors/node_lookup_test.go

Note to reviewers

In this pull request, I've introduced two new structs within flytepropeller/pkg/controller/executors/kube_test.go: FakeReader and FakeObject.
Since these structs are not yet implemented in Flytepropeller, I could not generate mock objects for testing purposes.
This is the reason behind the current implementation.

Update:
Due to this revert, I have to update my test code.

Check all the applicable boxes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

Screenshots

Before

After

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (b6b0d61) 59.53% compared to head (42ec719) 59.31%.
Report is 3 commits behind head on master.

❗ Current head 42ec719 differs from pull request most recent head f2edb21. Consider uploading reports for the commit f2edb21 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4276      +/-   ##
==========================================
- Coverage   59.53%   59.31%   -0.23%     
==========================================
  Files         632      544      -88     
  Lines       53527    38933   -14594     
==========================================
- Hits        31867    23092    -8775     
+ Misses      19145    13561    -5584     
+ Partials     2515     2280     -235     

Flag	Coverage Δ
unittests	?

Flags with carried forward coverage won't be shown. Click here to find out more.

see 570 files with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[Future-Outlier]

I will add more tests in this dir...