Explain Spring Boot Observability and OpenTelemetry integration.

Observability provides metrics, traces, and logs:\n\n@RestController\npublic class ObservableController {\n \n @GetMapping("/api/users")\n @Observed(name = "user.fetch", contextualName = "fetch-users")\n public List getUsers() {\n return userService.findAll();\n }\n}\n\n# application.properties\nmanagement.tracing.sampling.probability=1.0\nmanagement.otlp.tracing.endpoint=http://jaeger:14268/api/traces\nmanagement.metrics.export.prometheus.enabled=true