test: rename CTransaction .rehash()/.hash -> .txid_hex for consistency

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

test/functional/interface_zmq.py

@@ -212,14 +212,14 @@ class ZMQTest (BitcoinTestFramework):
 
             # Should receive the coinbase raw transaction.
             tx = tx_from_hex(rawtx.receive().hex())
-            assert_equal(tx.hash, txid.hex())
+            assert_equal(tx.txid_hex, txid.hex())
 
             # Should receive the generated raw block.
             hex = rawblock.receive()
             block = CBlock()
             block.deserialize(BytesIO(hex))
             assert block.is_valid()
-            assert_equal(block.vtx[0].hash, tx.hash)
+            assert_equal(block.vtx[0].txid_hex, tx.txid_hex)
             assert_equal(len(block.vtx), 1)
             assert_equal(genhashes[x], hash256_reversed(hex[:80]).hex())