Limit supported annotations to @ConfigurationProperties and @Configuration

Previously, the configuration property annotation processor declared
that it supported all annotation types. This hurt performance and
prevented incremental builds with Gradle when compiling source code
containing source-retention annotations.

This commit updates its supported annotation types to be only
`@ConfigurationProperties` and `@Configuration`. The latter is declared
to allow binding third-party classes returned from a `@Bean` method.

Fixes gh-23580

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/main/java/org/springframework/boot/configurationprocessor/ConfigurationMetadataAnnotationProcessor.java

@@ -59,7 +59,8 @@ import org.springframework.boot.configurationprocessor.metadata.ItemMetadata;
  * @author Jonas Keßler
  * @since 1.2.0
  */
-@SupportedAnnotationTypes({ "*" })
+@SupportedAnnotationTypes({ ConfigurationMetadataAnnotationProcessor.CONFIGURATION_PROPERTIES_ANNOTATION,
+		"org.springframework.context.annotation.Configuration" })
 public class ConfigurationMetadataAnnotationProcessor extends AbstractProcessor {
 
 	static final String ADDITIONAL_METADATA_LOCATIONS_OPTION = "org.springframework.boot.configurationprocessor.additionalMetadataLocations";