scripted-diff: test: rename CTransaction .getwtxid() -> wtxid_hex for consistency

-BEGIN VERIFY SCRIPT-

sed -i "s|def getwtxid|@property\n    def wtxid_hex|g" ./test/functional/test_framework/messages.py
sed -i "s|getwtxid()|wtxid_hex|g" $(git grep -l getwtxid)

-END VERIFY SCRIPT-

test/functional/mempool_accept_wtxid.py

@@ -76,13 +76,13 @@ class MempoolWtxidTest(BitcoinTestFramework):
         child_one.vout.append(CTxOut(int(9.99996 * COIN), child_script_pubkey))
         child_one.wit.vtxinwit.append(CTxInWitness())
         child_one.wit.vtxinwit[0].scriptWitness.stack = [b'Preimage', b'\x01', witness_script]
-        child_one_wtxid = child_one.getwtxid()
+        child_one_wtxid = child_one.wtxid_hex
         child_one_txid = child_one.txid_hex
 
         # Create another identical transaction with witness solving second branch
         child_two = deepcopy(child_one)
         child_two.wit.vtxinwit[0].scriptWitness.stack = [b'', witness_script]
-        child_two_wtxid = child_two.getwtxid()
+        child_two_wtxid = child_two.wtxid_hex
         child_two_txid = child_two.txid_hex
 
         assert_equal(child_one_txid, child_two_txid)