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_create_tx.py

@@ -17,9 +17,6 @@ from test_framework.blocktools import (
 
 
 class CreateTxWalletTest(BitcoinTestFramework):
-    def add_options(self, parser):
-        self.add_wallet_options(parser)
-
     def set_test_params(self):
         self.setup_clean_chain = True
         self.num_nodes = 1