test: rename CTransaction .sha256 -> .txid_int for consistency

Note that we unfortunately can't use a scripted diff here, as the same
property name is also used for `CBlockHeader`/`CBlock` instances.

test/functional/test_framework/blocktools.py

@@ -187,7 +187,7 @@ def create_tx_with_script(prevtx, n, script_sig=b"", *, amount, output_script=No
         output_script = CScript()
     tx = CTransaction()
     assert n < len(prevtx.vout)
-    tx.vin.append(CTxIn(COutPoint(prevtx.sha256, n), script_sig, SEQUENCE_FINAL))
+    tx.vin.append(CTxIn(COutPoint(prevtx.txid_int, n), script_sig, SEQUENCE_FINAL))
     tx.vout.append(CTxOut(amount, output_script))
     return tx