tests: Add missing sync_all to wallet_importdescriptors.py

node1 will sometimes do sendtoaddress before it has received a funding
transaction which will cause the test to fail. sync_all to ensure it
gets the transaction first.

test/functional/wallet_importdescriptors.py

@@ -331,6 +331,7 @@ def run_test(self):
         assert_equal(wmulti_priv.getwalletinfo()['keypoolsize'], 1000)
         txid = w0.sendtoaddress(addr, 10)
         self.nodes[0].generate(6)
+        self.sync_all()
         send_txid = wmulti_priv.sendtoaddress(w0.getnewaddress(), 8)
         decoded = wmulti_priv.decoderawtransaction(wmulti_priv.gettransaction(send_txid)['hex'])
         assert_equal(len(decoded['vin'][0]['txinwitness']), 4)