[Exporter.Geneva] Update OTel SDK version to 1.5.0 and remove Exemplars support

[utpilla]

Changes

• Update OTel SDK version to 1.5.0
• Remove Exemplars support

For significant contributions please make sure you have completed the following items:

• Appropriate CHANGELOG.md updated for non-trivial changes

[codecov]

Codecov Report

Merging #1238 (e551255) into main (dbfeaea) will decrease coverage by 0.65%.
The diff coverage is n/a.

❗ Current head e551255 differs from pull request most recent head 1008d5c. Consider uploading reports for the commit 1008d5c to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1238      +/-   ##
==========================================
- Coverage   73.61%   72.97%   -0.65%     
==========================================
  Files         265      265              
  Lines        9346     9279      -67     
==========================================
- Hits         6880     6771     -109     
- Misses       2466     2508      +42     

Impacted Files	Coverage Δ
...ry.Exporter.Geneva/Metrics/GenevaMetricExporter.cs	70.03% <ø> (-4.52%)	⬇️

... and 1 file with indirect coverage changes