scripted-diff: Use wallets_path and chain_path where possible

Instead of passing the datadir and chain name to os.path.join, just use
the existing properties, which are the same.

-BEGIN VERIFY SCRIPT-
 sed -i --regexp-extended 's|\.datadir, self\.chain, .wallets.|.wallets_path|g' $(git grep -l '\.datadir, self\.chain,')
 sed -i --regexp-extended 's|\.datadir, self\.chain,|.chain_path,|g'            $(git grep -l '\.datadir, self\.chain,')
-END VERIFY SCRIPT-

test/functional/wallet_reorgsrestore.py

@@ -89,7 +89,7 @@ class ReorgsRestoreTest(BitcoinTestFramework):
         # Node0 wallet file is loaded on longest sync'ed node1
         self.stop_node(1)
         self.nodes[0].backupwallet(os.path.join(self.nodes[0].datadir, 'wallet.bak'))
-        shutil.copyfile(os.path.join(self.nodes[0].datadir, 'wallet.bak'), os.path.join(self.nodes[1].datadir, self.chain, self.default_wallet_name, self.wallet_data_filename))
+        shutil.copyfile(os.path.join(self.nodes[0].datadir, 'wallet.bak'), os.path.join(self.nodes[1].chain_path, self.default_wallet_name, self.wallet_data_filename))
         self.start_node(1)
         tx_after_reorg = self.nodes[1].gettransaction(txid)
         # Check that normal confirmed tx is confirmed again but with different blockhash