Do not run UI tests in the error-emitter directory

Author: antoyo

build_system/src/test.rs

@@ -876,9 +876,14 @@ fn contains_ui_error_patterns(file_path: &Path, keep_lto_tests: bool) -> Result<
             return Ok(true);
         }
     }
-    if file_path.display().to_string().contains("ambiguous-4-extern.rs") {
+    let file_path = file_path.display().to_string();
+    if file_path.contains("ambiguous-4-extern.rs") {
         eprintln!("nothing found for {file_path:?}");
     }
+    // The files in this directory contain errors.
+    if file_path.contains("/error-emitter/") {
+        return Ok(true);
+    }
     Ok(false)
 }