Include properties from test-autoconfigure in config props appendix

Closes gh-24486

Author: wilkinsona

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

@@ -60,6 +60,7 @@ dependencies {
 	configurationProperties(project(path: ":spring-boot-project:spring-boot-actuator-autoconfigure", configuration: "configurationPropertiesMetadata"))
 	configurationProperties(project(path: ":spring-boot-project:spring-boot-autoconfigure", configuration: "configurationPropertiesMetadata"))
 	configurationProperties(project(path: ":spring-boot-project:spring-boot-devtools", configuration: "configurationPropertiesMetadata"))
+	configurationProperties(project(path: ":spring-boot-project:spring-boot-test-autoconfigure", configuration: "configurationPropertiesMetadata"))
 
 	gradlePluginDocumentation(project(path: ":spring-boot-project:spring-boot-tools:spring-boot-gradle-plugin", configuration: "documentation"))
 

spring-boot-project/spring-boot-test-autoconfigure/build.gradle

@@ -82,6 +82,16 @@ dependencies {
 	testRuntimeOnly("org.junit.platform:junit-platform-launcher")
 }
 
+configurations {
+	configurationPropertiesMetadata
+}
+
+artifacts {
+	configurationPropertiesMetadata new File(sourceSets.main.output.resourcesDir, "META-INF/spring-configuration-metadata.json"), { artifact ->
+		artifact.builtBy sourceSets.main.processResourcesTaskName
+	}
+}
+
 test {
 	include "**/*Tests.class"
 }