Make auto-configured OtelTracer back off when user defines a Tracer

Closes gh-33097

Author: wilkinsona

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/tracing/OpenTelemetryAutoConfiguration.java

@@ -135,7 +135,7 @@ Tracer otelTracer(OpenTelemetry openTelemetry) {
 	}
 
 	@Bean
-	@ConditionalOnMissingBean
+	@ConditionalOnMissingBean(io.micrometer.tracing.Tracer.class)
 	OtelTracer micrometerOtelTracer(Tracer tracer, EventPublisher eventPublisher,
 			OtelCurrentTraceContext otelCurrentTraceContext) {
 		return new OtelTracer(tracer, otelCurrentTraceContext, eventPublisher,

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/tracing/OpenTelemetryAutoConfigurationTests.java

@@ -106,8 +106,8 @@ void shouldNotSupplyBeansIfDependencyIsMissing(String packageName) {
 	@Test
 	void shouldBackOffOnCustomBeans() {
 		this.contextRunner.withUserConfiguration(CustomConfiguration.class).run((context) -> {
-			assertThat(context).hasBean("customOtelTracer");
-			assertThat(context).hasSingleBean(OtelTracer.class);
+			assertThat(context).hasBean("customMicrometerTracer");
+			assertThat(context).hasSingleBean(io.micrometer.tracing.Tracer.class);
 			assertThat(context).hasBean("customEventPublisher");
 			assertThat(context).hasSingleBean(EventPublisher.class);
 			assertThat(context).hasBean("customOtelCurrentTraceContext");
@@ -201,8 +201,8 @@ void shouldSupplyW3CPropagationWithoutBaggageWhenDisabled() {
 	private static class CustomConfiguration {
 
 		@Bean
-		OtelTracer customOtelTracer() {
-			return mock(OtelTracer.class);
+		io.micrometer.tracing.Tracer customMicrometerTracer() {
+			return mock(io.micrometer.tracing.Tracer.class);
 		}
 
 		@Bean