fix(sdk-metrics): allow instrument names to contain '/'

[aabmass]

Which problem is this PR solving?

Fixes #4141

Short description of the changes

Allows the / character in metric instrument name validation.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Updated existing test case

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added
• Documentation has been updated – N/A

[codecov]

Codecov Report

Merging #4155 (9976b38) into main (1a8652a) will increase coverage by 0.01%.
The diff coverage is 100.00%.

❗ Current head 9976b38 differs from pull request most recent head 71bc38d. Consider uploading reports for the commit 71bc38d to get more accurate results

@@            Coverage Diff             @@
##             main    #4155      +/-   ##
==========================================
+ Coverage   92.29%   92.30%   +0.01%     
==========================================
  Files         328      328              
  Lines        9385     9385              
  Branches     1993     1993              
==========================================
+ Hits         8662     8663       +1     
+ Misses        723      722       -1     

Files Changed	Coverage
packages/sdk-metrics/src/InstrumentDescriptor.ts	100.00%

[pichlermarc]

Looks good, thanks! 🙂
Edit: failing windows test is unrelated - looks like some server is unavailable/misbehaving - I'll restart the test.