[introspection] Make green on .NET/Mac Catalyst. Fixes #10215.

[rolfbjarne]

• [catalyst] ignored introspection failures for native symbols #10883 only applies to Mac Catalyst for legacy Xamarin.
• Ignore the ApiAvailabilityTest.LegacyAttribute test on Mac Catalyst as well.
• introspection is now green on .NET/Mac Catalyst, so enable it in xharness.

Fixes #10215.

[vs-mobiletools-engineering-service2]

❌ [PR Build] Tests failed on Build ❌

Tests failed on Build.

• Azure DevOps
• Html Report (VSDrops)

API diff

✅ API Diff from stable

View API diff

• iOS vsdrops gist
• macOS vsdrops gist
• macCat vsdrops gist
• macCatiOS gist
• tvOS vsdrops gist
• watchOS vsdrops gist

API & Generator diff

✅ API Diff (from PR only) (no change)
✅ Generator Diff (no change)

GitHub pages

Results can be found in the following github pages (it might take some time to publish):

• Test results
• API diff
• API & Generator diff

Test results

2 tests failed, 120 tests passed.

Failed tests

• monotouch-test/Mac Catalyst/Debug [dotnet]: Failed (Tests run: 2629 Passed: 2489 Inconclusive: 35 Failed: 2 Ignored: 138)
• xcframework-test/Mac Catalyst/Debug: TimedOut (Execution timed out after 1200 seconds.
  No test log file was produced)

Pipeline on Agent XAMBOT-1104.BigSur'
Merge c0516a0 into 8bfa366

[rolfbjarne]

Test failures are unrelated:

• monotouch-test/Mac Catalyst/Debug [dotnet]: https://github.com/xamarin/maccore/issues/2443
• xcframework-test/Mac Catalyst/Debug: https://github.com/xamarin/maccore/issues/2414