Resolve proposal from #11505 PR discussion

Cf. https://github.com/apache/maven/pull/11505/files#r2622241004

Author: ascheman

impl/maven-core/src/main/java/org/apache/maven/project/DefaultProjectBuilder.java

@@ -686,8 +686,8 @@ private void initProject(MavenProject project, ModelBuilderResult result) {
                         ProjectScope scope = src.scope();
                         if (ProjectScope.MAIN.equals(scope)) {
                             hasMainResources = true;
-                        } else {
-                            hasTestResources |= ProjectScope.TEST.equals(scope);
+                        } else if (ProjectScope.TEST.equals(scope)) {
+                            hasTestResources = true;
                         }
                     } else {
                         hasScript |= Language.SCRIPT.equals(language);