Make clean remove the root build folder

Closes gh-28857

build.gradle

@@ -1,4 +1,5 @@
 plugins {
+	id "base"
 	id "org.jetbrains.kotlin.jvm" apply false // https://youtrack.jetbrains.com/issue/KT-30276
 	id "io.spring.nohttp" version "0.0.10"
 }
@@ -16,7 +17,7 @@ nohttp {
 	source.exclude "spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/test/resources/org/springframework/boot/buildpack/platform/docker/export.tar"
 }
 
-task build {
+check {
 	dependsOn checkstyleNohttp
 }
 

settings.gradle

@@ -36,12 +36,12 @@ settings.gradle.projectsLoaded {
 				value('Toolchain version', toolchainVersion)
 				tag("JDK-$toolchainVersion")
 			}
-
+			def buildDir = settings.gradle.rootProject.getBuildDir()
-			settings.gradle.rootProject.getBuildDir().mkdirs()
+			buildDir.mkdirs()
-			new File(settings.gradle.rootProject.getBuildDir(), "build-scan-uri.txt").text = "build scan not generated"
+			new File(buildDir, "build-scan-uri.txt").text = "build scan not generated"
-
 			buildScanPublished { scan ->
-				new File(settings.gradle.rootProject.getBuildDir(), "build-scan-uri.txt").text = "<${scan.buildScanUri}|build scan>\n"
+				buildDir.mkdirs()
+				new File(buildDir, "build-scan-uri.txt").text = "<${scan.buildScanUri}|build scan>\n"
 			}
 		}
 	}