fix(eslint-plugin): [no-unused-vars] fix race condition between naming-convention and no-unused-vars

[bradzacher]

Fixes #2844

[typescript-eslint]

Thanks for the PR, @bradzacher!

typescript-eslint is a 100% community driven project, and we are incredibly grateful that you are contributing to that community.

The core maintainers work on this in their personal time, so please understand that it may not be possible for them to review your work immediately.

Thanks again!

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[codecov]

Codecov Report

Merging #2848 (f022c81) into master (fed89f2) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2848      +/-   ##
==========================================
+ Coverage   92.73%   92.75%   +0.02%     
==========================================
  Files         309      309              
  Lines       10332    10335       +3     
  Branches     2926     2927       +1     
==========================================
+ Hits         9581     9586       +5     
+ Misses        347      346       -1     
+ Partials      404      403       -1     

Flag	Coverage Δ
unittest	92.75% <100.00%> (+0.02%)	⬆️

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

Impacted Files	Coverage Δ
packages/eslint-plugin/src/rules/no-unused-vars.ts	96.68% <100.00%> (+0.06%)	⬆️
...s/eslint-plugin/src/util/collectUnusedVariables.ts	92.01% <0.00%> (+0.84%)	⬆️