[Instrumentation.AspNet] Rename Enrich metrics options

[Kielek]

Towards #2909

Changes

Change Enrich options to make it consistent with other Enrich methods.

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
• Unit tests added/updated
• Appropriate CHANGELOG.md files updated for non-trivial changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.85%. Comparing base (b0d5cd4) to head (0ff0edf).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3070      +/-   ##
==========================================
+ Coverage   69.70%   69.85%   +0.15%     
==========================================
  Files         420      410      -10     
  Lines       16340    16228     -112     
==========================================
- Hits        11389    11336      -53     
+ Misses       4951     4892      -59     

Flag	Coverage Δ
unittests-Instrumentation.AspNet	74.93% <100.00%> (ø)
unittests-Instrumentation.Cassandra	?

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

Files with missing lines	Coverage Δ
...tion.AspNet/AspNetMetricsInstrumentationOptions.cs	100.00% <100.00%> (ø)
...umentation.AspNet/Implementation/HttpInListener.cs	80.41% <100.00%> (ø)

... and 16 files with indirect coverage changes

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[alanwest]

LGTM. Mostly aligns with what we did with ASP.NET Core.