fix: the `Maven Project Builder' duplicate issue

 uncheck it then do `maven -> Update Project...` we'll see the duplicate

Author: qxo

org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/project/ProjectConfigurationManager.java

@@ -653,7 +653,10 @@ public boolean removeMavenBuilder(IProject project, IProjectDescription descript
   }
 
   private boolean isMavenBuilderCommand(ICommand command) {
-    return IMavenConstants.BUILDER_ID.equals(command.getBuilderName());
+    final String name = command.getBuilderName();
+    return IMavenConstants.BUILDER_ID.equals(name) 
+      || "org.eclipse.ui.externaltools.ExternalToolBuilder".equals(name)
+        && command.getArguments().toString().contains("LaunchConfigHandle=<project>/.externalToolBuilders/org.eclipse.m2e.core.maven2Builder");
   }
 
   // project creation