chore: unify formatting in ISSUE_TEMPLATE's

[rauno56]

Saw something that should've been commented out, but wasn't while making an issue, went through all other templates as well.
I know a lot is in being changed because of coming GA, so if it harms more than does good(perhaps those or conflicting changes are already in a branch somewhere), just close and forget it.

Which problem is this PR solving?

It unifies formatting across ISSUE_TEMPLATE files.

Short description of the changes

• Comment out everything, that's describing how to put together the issue and should not land in the final presented text,
• Consistent whitespace
• Change bold to H3 everywhere, bug_report.md had one, feature and plugin requests had bold.

[codecov]

Codecov Report

Merging #426 (f152c8e) into main (1e2a165) will not change coverage.
The diff coverage is n/a.

❗ Current head f152c8e differs from pull request most recent head 6312ebb. Consider uploading reports for the commit 6312ebb to get more accurate results

@@           Coverage Diff           @@
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  Coverage   95.83%   95.83%           
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  Files          15       15           
  Lines         624      624           
  Branches       94       94           
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  Hits          598      598           
  Misses         26       26           

[obecny]

lgtm, just some tiny interpunction