IDEA project configuration: use JUnit3 library with 'Test' scope only

The library isn't used by the IDE, it's kept only for compatibility with users' projects, so switching dependency scope helps to avoid messages about conflicting library versions (see IDEA-204495).

build/groovy/org/jetbrains/intellij/build/BaseIdeaProperties.groovy

@@ -125,6 +125,7 @@ abstract class BaseIdeaProperties extends ProductProperties {
         withoutProjectLibrary("Ant")
         withoutProjectLibrary("Gradle")
         removeVersionFromProjectLibraryJarNames("jetbrains-annotations")
+        withProjectLibrary("JUnit3")
         removeVersionFromProjectLibraryJarNames("JUnit3") //for compatibility with users projects which refer to IDEA_HOME/lib/junit.jar
       }
     } as Consumer<PlatformLayout>

plugins/junit/intellij.junit.iml

@@ -13,7 +13,7 @@
     <orderEntry type="module" module-name="intellij.java.execution.impl" />
     <orderEntry type="module" module-name="intellij.java.rt" />
     <orderEntry type="module" module-name="intellij.platform.testRunner" />
-    <orderEntry type="library" name="JUnit3" level="project" />
+    <orderEntry type="library" scope="TEST" name="JUnit3" level="project" />
     <orderEntry type="library" name="JUnit4" level="project" />
     <orderEntry type="module" module-name="intellij.junit.rt" />
     <orderEntry type="module" module-name="intellij.java.compiler" />