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/feature_dersig.py

@@ -115,7 +115,7 @@ class BIP66Test(BitcoinTestFramework):
         # First we show that this tx is valid except for DERSIG by getting it
         # rejected from the mempool for exactly that reason.
         spendtx_txid = spendtx.txid_hex
-        spendtx_wtxid = spendtx.getwtxid()
+        spendtx_wtxid = spendtx.wtxid_hex
         assert_equal(
             [{
                 'txid': spendtx_txid,