Use Gradle's configuration avoidance APIs in the reference docs

See gh-30000

spring-boot-project/spring-boot-docs/src/docs/asciidoc/configuration-metadata/annotation-processor.adoc

@@ -33,7 +33,9 @@ If you are using an `additional-spring-configuration-metadata.json` file, the `c
 
 [source,gradle,indent=0,subs="verbatim"]
 ----
-	compileJava.inputs.files(processResources)
+	tasks.named('compileJava') {
+	    inputs.files(tasks.named('processResources'))
+	}
 ----
 
 This dependency ensures that the additional metadata is available when the annotation processor runs during compilation.

spring-boot-project/spring-boot-docs/src/docs/asciidoc/deployment/installing.adoc

@@ -30,7 +30,7 @@ The following example shows the equivalent Gradle configuration:
 
 [source,gradle,indent=0,subs="verbatim"]
 ----
-	bootJar {
+	tasks.named('bootJar') {
 		launchScript()
 	}
 ----

spring-boot-project/spring-boot-docs/src/docs/asciidoc/howto/properties-and-configuration.adoc

@@ -71,7 +71,7 @@ You can automatically expand properties from the Gradle project by configuring t
 
 [source,gradle,indent=0,subs="verbatim"]
 ----
-	processResources {
+	tasks.named('processResources') {
 		expand(project.properties)
 	}
 ----