test: Remove wallet option from non-wallet tests

Review note: The changes are complete, because self.options.descriptors
is set to None in parse_args (test_framework.py).

A value of None implies -disablewallet, see the previous commit.

So if a call to add_wallet_options is missing, it will lead to a test
failure when the wallet is compiled in.

test/functional/mempool_unbroadcast.py

@@ -15,6 +15,9 @@ from test_framework.wallet import MiniWallet
 MAX_INITIAL_BROADCAST_DELAY = 15 * 60 # 15 minutes in seconds
 
 class MempoolUnbroadcastTest(BitcoinTestFramework):
+    def add_options(self, parser):
+        self.add_wallet_options(parser)
+
     def set_test_params(self):
         self.num_nodes = 2