tests: Remove unused testing code

test/functional/test_runner.py

@@ -635,7 +635,7 @@ class RPCCoverage():
         with open(coverage_ref_filename, 'r', encoding="utf8") as coverage_ref_file:
             all_cmds.update([line.strip() for line in coverage_ref_file.readlines()])
 
-        for root, dirs, files in os.walk(self.dir):
+        for root, _, files in os.walk(self.dir):
             for filename in files:
                 if filename.startswith(coverage_file_prefix):
                     coverage_filenames.add(os.path.join(root, filename))