Remove boilerplate golang_dockerfile

[eapolinario]

Tracking issue

N/A

Why are the changes needed?

boilerplate is integrated into the monorepo. There's no need to maintain a template and since it's not being used it only collects dust (and security warnings - e.g. https://app.snyk.io/org/flyte/project/aa4ebd2e-a393-4f26-bf50-4dab0f094ae0).

What changes were proposed in this pull request?

Remove the golang_dockerfile directory from boilerplate.

How was this patch tested?

Setup process

Screenshots

Check all the applicable boxes

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

Related PRs

Docs link

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.00%. Comparing base (c10346d) to head (8738fc6).
Report is 132 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5495      +/-   ##
==========================================
- Coverage   61.01%   61.00%   -0.01%     
==========================================
  Files         794      794              
  Lines       51441    51441              
==========================================
- Hits        31388    31384       -4     
- Misses      17161    17165       +4     
  Partials     2892     2892              

Flag	Coverage Δ
unittests-datacatalog	69.31% <ø> (ø)
unittests-flyteadmin	58.73% <ø> (ø)
unittests-flytecopilot	17.79% <ø> (ø)
unittests-flytectl	68.03% <ø> (-0.06%)	⬇️
unittests-flyteidl	79.04% <ø> (ø)
unittests-flyteplugins	61.85% <ø> (ø)
unittests-flytepropeller	57.30% <ø> (ø)
unittests-flytestdlib	65.80% <ø> (-0.03%)	⬇️

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