scripted-diff: Remove setup_clean_chain if default is not changed

-BEGIN VERIFY SCRIPT-
git grep -l "self.setup_clean_chain = False" test/functional/*.py | xargs sed -i "/self.setup_clean_chain = False/d";
-END VERIFY SCRIPT-

test/functional/feature_dbcrash.py

@@ -49,7 +49,6 @@ from test_framework.util import (
 class ChainstateWriteCrashTest(BitcoinTestFramework):
     def set_test_params(self):
         self.num_nodes = 4
-        self.setup_clean_chain = False
         self.rpc_timeout = 480
         self.supports_cli = False