metrics: enforce more otel/prometheus aligned names

[mstoykov]

Closes #3065

[codecov-commenter]

Codecov Report

Attention: 53 lines in your changes are missing coverage. Please review.

Comparison is base (0db029a) 73.34% compared to head (3019269) 73.35%.
Report is 5 commits behind head on master.

❗ Current head 3019269 differs from pull request most recent head 498222e. Consider uploading reports for the commit 498222e to get more accurate results

Files	Patch %	Lines
js/modules/k6/experimental/fs/errors_gen.go	9.09%	19 Missing and 1 partial ⚠️
js/modules/k6/experimental/fs/module.go	84.25%	11 Missing and 9 partials ⚠️
js/modules/k6/experimental/fs/cache.go	55.55%	4 Missing and 4 partials ⚠️
loader/loader.go	78.94%	2 Missing and 2 partials ⚠️
js/modules/k6/experimental/fs/errors.go	80.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           master    #3448    +/-   ##
========================================
  Coverage   73.34%   73.35%            
========================================
  Files         261      266     +5     
  Lines       19769    19956   +187     
========================================
+ Hits        14500    14639   +139     
- Misses       4371     4407    +36     
- Partials      898      910    +12     

Flag	Coverage Δ
ubuntu	73.29% <80.37%> (+0.03%)	⬆️
windows	73.19% <80.37%> (+<0.01%)	⬆️

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[mstoykov]

I reedited the message while fixing the test as it seemed strange to not start with what it should include and letter needed to become ASCII letter

But we can edit it more or revert it.