remove net461 from windows-ci-md, add net462

[TimothyMothra]

Towards #3190

Changes

• updates "windows-ci-md", removes net461, adds net462.
  follow-up to Remove net461 from jaeger zipkin and otlp exporters #3194 which updated "windows-ci"

Please provide a brief description of the changes here.

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

• Appropriate CHANGELOG.md updated for non-trivial changes
• Design discussion issue #
• Changes in public API reviewed

[codecov]

Codecov Report

Merging #3199 (86a66b0) into main (2f8bcc4) will increase coverage by 0.08%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #3199      +/-   ##
==========================================
+ Coverage   85.17%   85.26%   +0.08%     
==========================================
  Files         259      259              
  Lines        9345     9345              
==========================================
+ Hits         7960     7968       +8     
+ Misses       1385     1377       -8     

Impacted Files	Coverage Δ
...metryProtocol/Implementation/ActivityExtensions.cs	92.34% <0.00%> (+0.90%)	⬆️
...nTelemetry/Internal/OpenTelemetrySdkEventSource.cs	76.72% <0.00%> (+2.58%)	⬆️
...lemetry/Internal/SelfDiagnosticsConfigRefresher.cs	89.42% <0.00%> (+2.88%)	⬆️

[TimothyMothra]

@cijothomas looks like the branch rules need to be updated.
This would be in Settings > Branches > Branch protection rules.

• remove "build-test (net461)"
  

• add "build-test (net462)" to be required