Add back aspnetcore instrumentation in example

[cijothomas]

Add back instrumentation which got accidentally removed in #2989

[codecov]

Codecov Report

Merging #3021 (1772fcd) into main (d55de34) will increase coverage by 0.02%.
The diff coverage is n/a.

❗ Current head 1772fcd differs from pull request most recent head c0c59eb. Consider uploading reports for the commit c0c59eb to get more accurate results

@@            Coverage Diff             @@
##             main    #3021      +/-   ##
==========================================
+ Coverage   84.15%   84.17%   +0.02%     
==========================================
  Files         258      258              
  Lines        9093     9093              
==========================================
+ Hits         7652     7654       +2     
+ Misses       1441     1439       -2     

Impacted Files	Coverage Δ
...Telemetry/Internal/SelfDiagnosticsEventListener.cs	96.87% <0.00%> (-0.79%)	⬇️
...nTelemetry/Internal/OpenTelemetrySdkEventSource.cs	73.68% <0.00%> (+0.87%)	⬆️
...emetry.Api/Internal/OpenTelemetryApiEventSource.cs	82.35% <0.00%> (+5.88%)	⬆️

[cijothomas]

Merging, intentionally ignoring the APIcompact failure (its flaky) as this PR is only touching examples, so no risk.