Add spring-boot-micrometer-tracing to spring-boot-starter-zipkin

This also adds io.micrometer:micrometer-tracing-bridge-brave to the
Zipkin starter, otherwise we'd get no traces exported.

This also adds spring-boot-micrometer-tracing-test to the Zipkin test
starter.

Closes gh-47866

starter/spring-boot-starter-zipkin-test/build.gradle

@@ -22,5 +22,8 @@ description = "Starter for testing Zipkin"
 
 dependencies {
 	api(project(":starter:spring-boot-starter-test"))
+
 	api(project(":starter:spring-boot-starter-zipkin"))
+
+	api(project(":module:spring-boot-micrometer-tracing-test"))
 }

starter/spring-boot-starter-zipkin/build.gradle

@@ -23,5 +23,10 @@ description = "Starter for using Zipkin"
 dependencies {
 	api(project(":starter:spring-boot-starter"))
 
+	api(project(":module:spring-boot-micrometer-tracing"))
 	api(project(":module:spring-boot-zipkin"))
+
+	runtimeOnly("io.micrometer:micrometer-tracing-bridge-brave") {
+		exclude(group: "aopalliance", module: "aopalliance")
+	}
 }