Update baggage-processor module to follow style guide

[Copilot]

This PR updates the baggage-processor module to comply with the OpenTelemetry Java style guide recommendations, specifically addressing the following areas:

Changes Made

Final keyword usage

• Added final keyword to all public classes: BaggageProcessorCustomizer, BaggageSpanProcessor, and BaggageLogRecordProcessor
• Added final keyword to baggageKeyPredicate fields in processor classes

AutoService annotation

• Added @AutoService(AutoConfigurationCustomizerProvider.class) annotation to BaggageProcessorCustomizer
• Added necessary AutoService dependencies to build.gradle.kts (annotationProcessor, compileOnly, testImplementation)
• Removed manual META-INF/services/io.opentelemetry.sdk.autoconfigure.spi.AutoConfigurationCustomizerProvider file since @AutoService generates it automatically

Class organization

• Fixed class organization in BaggageLogRecordProcessor by moving the static allowAllBaggageKeys() method after instance fields and constructor, following the style guide's preferred order:
  • Instance fields
  • Constructors
  • Methods (static methods after instance methods)

Testing

All existing tests continue to pass, confirming that these changes are purely stylistic and don't affect functionality. The AutoService annotation correctly generates the service registration file at build time.

Fixes #373.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• scans-in.gradle.com
  • Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.lang.invoke=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.prefs/java.util.prefs=ALL-UNNAMED --add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED --add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.prefs/java.util.prefs=ALL-UNNAMED --add-opens=java.base/java.nio.charset=ALL-UNNAMED --add-opens=java.base/java.net=ALL-UNNAMED --add-opens=java.base/java.util.concurrent=ALL-UNNAMED --add-opens=java.base/java.util.concurrent.atomic=ALL-UNNAMED --add-opens=java.xml/javax.xml.namespace=ALL-UNNAMED -XX:MaxMetaspaceSize=512m -Dfile.encoding=UTF-8 -Duser.country -Duser.language=en -Duser.variant -cp /home/REDACTED/.gradle/wrapper/dists/gradle-9.0.0-bin/d6wjpkvcgsg3oed0qlfss3wgl/gradle-9.0.0/lib/gradle-daemon-main-9.0.0.jar -javaagent:/home/REDACTED/.gradle/wrapper/dists/gradle-9.0.0-bin/d6wjpkvcgsg3oed0qlfss3wgl/gradle-9.0.0/lib/agents/gradle-instrumentation-agent-9.0.0.jar org.gradle.launcher.daemon.bootstrap.GradleDaemon 9.0.0 (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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