Remove more rootProject references

Author: breskeby

build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/test/MutedTestPlugin.java

@@ -36,7 +36,7 @@ public void apply(Project project) {
             : "";
         List<RegularFile> additionalFiles = Arrays.stream(additionalFilePaths.split(","))
             .filter(p -> p.isEmpty() == false)
-            .map(p -> project.getRootProject().getLayout().getProjectDirectory().file(p))
+            .map(p -> project.getLayout().getSettingsDirectory().file(p))
             .toList();
 
         Provider<MutedTestsBuildService> mutedTestsProvider = project.getGradle()