Remove doc building from flytectl

[eapolinario]

Tracking issue

N/A

Why are the changes needed?

flytectl documentation is built in the monorepo. These remaining files under the flytectl directory are no longer being used and are just sources of false positives in security scanning.

What changes were proposed in this pull request?

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 (ce22670).
Report is 132 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5494      +/-   ##
==========================================
- 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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