Make EventSourceLoggerTest serialization trim safe

[Copilot]

Fixes #73438.

EventSourceLoggerTest used JsonConvert.SerializeObject behind an IL2026 suppression for complex EventSource payloads. This path was not trim/AOT safe.

• Manual complex payload serialization

  • Replaced the JsonConvert.SerializeObject fallback with JsonTextWriter-based serialization for the payload shapes emitted by these tests.
  • Handles dictionaries, key/value sequences, arrays, primitive values, enums, and nulls without reflection-based JSON serialization.

• Analyzer coverage

  • Removed the test project’s AOT analyzer opt-out now that the unsafe serialization call is gone.

[MichalStrehovsky]

/azp run runtime-nativeaot-outerloop

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[Copilot]

Pull request overview

Removes a trim/AOT unsafe JsonConvert.SerializeObject fallback in EventSourceLoggerTest's JSON payload helper, replacing it with explicit JsonTextWriter-based serialization that handles the specific payload shapes (dictionaries, key/value sequences, object arrays, primitives, enums, nulls). This allows the test project to re-enable the AOT analyzer and removes several ActiveIssue AOT skips.

Changes:

• Replaced JsonConvert.SerializeObject (with IL2026 suppression) with manual WriteComplexValue / WriteDictionary / WriteValue helpers and expanded IsPrimitive to cover all primitives, enums, decimal, DateTime, and Guid.
• Removed [ActiveIssue(... IsNativeAot)] attributes on four tests now that the unsafe path is gone.
• Removed the EnableAotAnalyzer=false opt-out from the test csproj.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/libraries/Microsoft.Extensions.Logging.EventSource/tests/EventSourceLoggerTest.cs	Replaces reflection-based JSON fallback with trim-safe manual serialization; widens IsPrimitive; removes NativeAOT ActiveIssue skips.
src/libraries/Microsoft.Extensions.Logging.EventSource/tests/Microsoft.Extensions.Logging.EventSource.Tests.csproj	Removes EnableAotAnalyzer=false opt-out now that the suppressed IL2026 call is gone.

[MichalStrehovsky]

The test was failing with trimming despite no trimming warnings. This was indeed a product bug like I wrote in #127449 (comment).

[MichalStrehovsky]

/azp run runtime-nativeaot-outerloop

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Azure Pipelines successfully started running 1 pipeline(s).