fix(sdk-metrics): do not report empty scopes and metrics

[pichlermarc]

Which problem is this PR solving?

This PR changes the behavior of the SDK to not report empty scopes (currently exported when a Meter is created, but never used), or empty metrics (instruments that were created, but never observed).

Fixes #4130
Partially addresses #4096 (now, never observed instruments are not exported).

Type of change

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

How Has This Been Tested?

• Adapted exisitng Tests

[codecov]

Codecov Report

Merging #4135 (228a8cb) into main (6bf1b78) will increase coverage by 0.02%.
The diff coverage is 94.44%.

❗ Current head 228a8cb differs from pull request most recent head c423a61. Consider uploading reports for the commit c423a61 to get more accurate results

@@            Coverage Diff             @@
##             main    #4135      +/-   ##
==========================================
+ Coverage   92.28%   92.30%   +0.02%     
==========================================
  Files         329      329              
  Lines        9370     9382      +12     
  Branches     1991     1996       +5     
==========================================
+ Hits         8647     8660      +13     
+ Misses        723      722       -1     

Files	Coverage Δ
packages/sdk-metrics/src/state/MetricCollector.ts	100.00% <100.00%> (ø)
...s/sdk-metrics/src/state/TemporalMetricProcessor.ts	98.30% <100.00%> (+0.09%)	⬆️
packages/sdk-metrics/src/state/MeterSharedState.ts	96.61% <83.33%> (+0.31%)	⬆️

... and 1 file with indirect coverage changes