Update processors module to follow style guide

[Copilot]

This PR updates the processors module to follow all recommendations in the style guide, making minimal changes as requested.

Changes Made

The main issue was with FilteringLogRecordProcessor which was not following the style guide conventions:

FilteringLogRecordProcessor.java

• Added final to class declaration (style guide requires public non-internal classes to be final where possible)
• Changed field visibility from public to private (following principle of minimal necessary visibility)
• Fields were already properly declared final

FilteringLogRecordProcessorTest.java

• Removed unnecessary anonymous subclass {} that was preventing the main class from being made final
• The anonymous subclass wasn't overriding any methods, so it was safe to remove

Verification

All other classes in the processors module were already correctly following the style guide:

• EventToSpanEventBridge - properly final with private final fields
• InterceptableSpanExporter - properly final with private final fields
• InterceptableLogRecordExporter - properly final with private final fields
• InterceptableMetricExporter - properly final with private final fields
• ComposableInterceptor - properly final with private final fields
• EventToSpanEventBridgeComponentProvider - correctly NOT final (internal package per style guide)

Static imports and code formatting were already compliant. All tests pass and ./gradlew spotlessApply was run to ensure proper formatting.

Fixes #405.

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