test: Remove w1_v18 from wallet backwards compatibility

This wallet is no longer used in the test

test/functional/wallet_backwards_compatibility.py

@@ -94,7 +94,6 @@ class BackwardsCompatibilityTest(BitcoinTestFramework):
         node_miner = self.nodes[0]
         node_master = self.nodes[1]
         node_v19 = self.nodes[self.num_nodes - 4]
-        node_v18 = self.nodes[self.num_nodes - 3]
         node_v17 = self.nodes[self.num_nodes - 2]
         node_v16 = self.nodes[self.num_nodes - 1]
 
@@ -145,13 +144,6 @@ class BackwardsCompatibilityTest(BitcoinTestFramework):
         assert wallet.getaddressinfo(address_18075)["solvable"]
         node_v19.unloadwallet("w1_v19")
 
-        # w1_v18: regular wallet, created with v0.18
-        node_v18.rpc.createwallet(wallet_name="w1_v18")
-        wallet = node_v18.get_wallet_rpc("w1_v18")
-        info = wallet.getwalletinfo()
-        assert info['private_keys_enabled']
-        assert info['keypoolsize'] > 0
-
         # w2: wallet with private keys disabled, created on master: update this
         #     test when default wallets private keys disabled can no longer be
         #     opened by older versions.