Closes #19496: remove glean metrics docs check from pre-push hook.

[mcomella]

Pull Request checklist

• Tests: This PR includes thorough tests or an explanation of why it does not
• Screenshots: This PR includes screenshots or GIFs of the changes made or an explanation of why it does not
• Accessibility: The code in this PR follows accessibility best practices or does not include any user facing features. In addition, it includes a screenshot of a successful accessibility scan to ensure no new defects are added to the product.

To download an APK when reviewing a PR:

1. click on Show All Checks,
2. click Details next to "Taskcluster (pull_request)" after it appears and then finishes with a green checkmark,
3. click on the "Fenix - assemble" task, then click "Run Artifacts".
4. the APK links should be on the left side of the screen, named for each CPU architecture

[codecov-commenter]

Codecov Report

Merging #19497 (51d33fc) into master (ede909e) will increase coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master   #19497      +/-   ##
============================================
+ Coverage     35.07%   35.09%   +0.01%     
  Complexity     1625     1625              
============================================
  Files           542      542              
  Lines         21883    21883              
  Branches       3250     3250              
============================================
+ Hits           7675     7679       +4     
+ Misses        13315    13313       -2     
+ Partials        893      891       -2     

Impacted Files	Coverage Δ	Complexity Δ
...in/java/org/mozilla/fenix/perf/NavGraphProvider.kt	62.50% <0.00%> (ø)	2.00% <0.00%> (-1.00%)
...components/toolbar/BrowserToolbarMenuController.kt	61.27% <0.00%> (+0.49%)	0.00% <0.00%> (ø%)
...java/org/mozilla/fenix/perf/PerformanceInflater.kt	95.00% <0.00%> (+15.00%)	5.00% <0.00%> (+1.00%)

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