test: rename CBlockHeader .hash -> .hash_hex for consistency

Note that we unfortunately can't use a scripted diff here, as the
`.hash` symbol is also used for other instances (e.g. CInv).

test/functional/feature_assumevalid.py

@@ -138,8 +138,8 @@ class AssumeValidTest(BitcoinTestFramework):
             height += 1
 
         # Start node1 and node2 with assumevalid so they accept a block with a bad signature.
-        self.start_node(1, extra_args=["-assumevalid=" + block102.hash])
-        self.start_node(2, extra_args=["-assumevalid=" + block102.hash])
+        self.start_node(1, extra_args=["-assumevalid=" + block102.hash_hex])
+        self.start_node(2, extra_args=["-assumevalid=" + block102.hash_hex])
 
         p2p0 = self.nodes[0].add_p2p_connection(BaseNode())
         p2p0.send_header_for_blocks(self.blocks[0:2000])