[sdk] Generate a consistent instanceId for the lifetime of a process

[CodeBlanch]

Fixes #4871

Changes

• Use a static Guid for service resource instance id so it is consistent across all signals when using the auto-generated path.

Merge requirement checklist

• CONTRIBUTING guidelines followed (nullable enabled, static analysis, etc.)
• Unit tests added/updated
• Appropriate CHANGELOG.md files updated for non-trivial changes

[codecov]

Codecov Report

Merging #4988 (cf4e6a0) into main (c0a5577) will decrease coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #4988      +/-   ##
==========================================
- Coverage   83.39%   83.35%   -0.05%     
==========================================
  Files         295      295              
  Lines       12336    12337       +1     
==========================================
- Hits        10288    10283       -5     
- Misses       2048     2054       +6     

Flag	Coverage Δ
unittests	83.35% <100.00%> (-0.05%)	⬇️

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

Files	Coverage Δ
...enTelemetry/Resources/ResourceBuilderExtensions.cs	100.00% <100.00%> (ø)

... and 6 files with indirect coverage changes