fix(otel): align service identity and Java ADOT initialization

[zhongkechen]

Summary

• standardize the deployed OpenTelemetry resource identity on durable-execution-conformance
• make X-Ray declare PLUGIN_MODE_SERVICE_NAME and query spans with the capitalized deployed OTEL_PLUGIN_MODE, removing the separate discovery service-name option
• initialize Java ADOT plugins through the Java-agent SPI and global tracer provider, exporting OTLP through the ADOT collector
• package the Java plugin as /var/task/lib/otel-plugin-extension.jar and enable the ADOT wrapper in regular and long-running templates
• retain the explicit tracer-provider builder for community OTLP endpoints and update workflows, documentation, and regression coverage

Testing

• JAVA_SDK_VERSION=2.1.1-SNAPSHOT mvn -B clean package --file packages/aws-durable-execution-conformance-tests-otel/examples/java/pom.xml (3 tests)
• hatch run test:all (339 tests)
• hatch run types:check
• hatch fmt --check
• hatch run yaml:lint
• sam build --template-file packages/aws-durable-execution-conformance-tests-otel/examples/java/template.yaml
• sam validate --lint for both Java templates
• git diff --check

Dependencies

• stacked on ci: continuously roll over long-running OTel tests #59; retarget to main after that PR merges
• paired Java SDK builder-path change: fix(otel): preserve configured service name aws-durable-execution-sdk-java#593