Transform Maven settings with proper plugin repository tag

This commit adapts d44e7c9 to transforms plugin repositories using the
correct root tag. Previously, they were transformed with the regular
<repository> tag, which is invalid.

Closes gh-42687

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-ant/build.gradle

@@ -50,7 +50,7 @@ task syncAntSources(type: Sync) {
 	destinationDir file("${buildDir}/ant")
 	from project.layout.projectDirectory
 	include "*.xml"
-	filter(springRepoistoryTransformers.ant())
+	filter(springRepositoryTransformers.ant())
 }
 
 task antRun(type: JavaExec) {