Update aws-resources module to follow style guide

[Copilot]

This PR updates the aws-resources module to follow the OpenTelemetry Java Contrib style guide by replacing manual service registration with @AutoService annotations.

Changes Made

• Added @AutoService annotations to all ResourceProvider implementations (BeanstalkResourceProvider, Ec2ResourceProvider, EcsResourceProvider, EksResourceProvider, LambdaResourceProvider) and the AwsResourceDetector class
• Made AwsResourceDetector final as it's in an internal package, following the style guide requirement that internal classes should be final where possible
• Updated build.gradle.kts to include AutoService dependencies:
  • annotationProcessor("com.google.auto.service:auto-service")
  • compileOnly("com.google.auto.service:auto-service")
  • testImplementation("com.google.auto.service:auto-service")
• Removed manual META-INF service registration files as they are now auto-generated by the @AutoService annotation processor

Benefits

• Follows style guide conventions: Uses @AutoService for SPI registration as recommended in the style guide
• Eliminates manual maintenance: Service registration files are now automatically generated at compile time
• Reduces errors: No need to manually maintain service registration files that can get out of sync
• Maintains backward compatibility: All existing functionality is preserved

The module now properly follows the OpenTelemetry Java Contrib style guide while maintaining all existing functionality. All tests continue to pass and the auto-generated service files are correctly included in the built JAR.

Fixes #234.

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