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/wallet_createwallet.py

@@ -17,7 +17,6 @@ from test_framework.wallet_util import bytes_to_wif, generate_wif_key
 
 class CreateWalletTest(BitcoinTestFramework):
     def set_test_params(self):
-        self.setup_clean_chain = False
         self.num_nodes = 1
 
     def skip_test_if_missing_module(self):