Avoid duplicate junit-platform.properties files caused by Kafka

Gradle doesn't support excluding a dependency that's declared with a
classifier. Instead, this commit replaces the test-qualified
kafka-server-common dependency with the plain dependency. The plain
dependency was already present so this is equivalent to excluding
the test-qualified dependency.

Closes gh-41446

spring-boot-project/spring-boot-docs/build.gradle

@@ -15,6 +15,15 @@ configurations {
 	springApplicationExample
 	testSlices
 	antoraContent
+	all {
+		resolutionStrategy.eachDependency { DependencyResolveDetails details ->
+			if (details.requested.module.group == "org.apache.kafka" && details.requested.module.name == "kafka-server-common") {
+				details.artifactSelection {
+					selectArtifact(DependencyArtifact.DEFAULT_TYPE, null, null)
+				}
+			}
+		}
+	}
 }
 
 jar {