test: remove legacy wallet functional tests

Removes all legacy wallet specific functional tests.

Also removes the --descriptor and --legacy-wallet options as these are
no longer necessary with the legacy wallet removed.

test/functional/wallet_txn_clone.py

@@ -26,7 +26,6 @@ class TxnMallTest(BitcoinTestFramework):
         self.skip_if_no_wallet()
 
     def add_options(self, parser):
-        self.add_wallet_options(parser)
         parser.add_argument("--mineblock", dest="mine_block", default=False, action="store_true",
                             help="Test double-spend of 1-confirmed transaction")
         parser.add_argument("--segwit", dest="segwit", default=False, action="store_true",