Add Embabel Observability Configuration

[alexheifetz]

This pull request updates the observability setup for the Java and Kotlin example projects by switching from Spring Boot's native tracing libraries to Embabel's observability agent and OpenTelemetry for Zipkin exporting. Configuration files are updated to enable and configure Embabel observability. The most important changes are:

Dependency and Observability Library Changes:

• Replaced Spring Boot Actuator, Micrometer tracing, and Zipkin Brave dependencies with embabel-agent-starter-observability and opentelemetry-exporter-zipkin in pom.xml, aligning observability with Embabel's stack.

Configuration Updates:

• Added embabel.observability configuration sections to both examples-java/src/main/resources/application-observability.yml and examples-kotlin/src/main/resources/application-observability.yml to enable Embabel observability and set the service name for each example project. [1] [2]
• Removed outdated comments in the configuration files indicating that observability was an application concern rather than a library concern, reflecting the move to library-managed observability. [1] [2]