scripted-diff: Rename hash_serialized_2 to hash_serialized_3

-BEGIN VERIFY SCRIPT-
sed -i 's/hash_serialized_2/hash_serialized_3/g' $( git grep -l 'hash_serialized_2' ./src ./contrib ./test )
-END VERIFY SCRIPT-

test/functional/feature_coinstatsindex.py

@@ -293,11 +293,11 @@ class CoinStatsIndexTest(BitcoinTestFramework):
     def _test_index_rejects_hash_serialized(self):
         self.log.info("Test that the rpc raises if the legacy hash is passed with the index")
 
-        msg = "hash_serialized_2 hash type cannot be queried for a specific block"
-        assert_raises_rpc_error(-8, msg, self.nodes[1].gettxoutsetinfo, hash_type='hash_serialized_2', hash_or_height=111)
+        msg = "hash_serialized_3 hash type cannot be queried for a specific block"
+        assert_raises_rpc_error(-8, msg, self.nodes[1].gettxoutsetinfo, hash_type='hash_serialized_3', hash_or_height=111)
 
         for use_index in {True, False, None}:
-            assert_raises_rpc_error(-8, msg, self.nodes[1].gettxoutsetinfo, hash_type='hash_serialized_2', hash_or_height=111, use_index=use_index)
+            assert_raises_rpc_error(-8, msg, self.nodes[1].gettxoutsetinfo, hash_type='hash_serialized_3', hash_or_height=111, use_index=use_index)
 
     def _test_init_index_after_reorg(self):
         self.log.info("Test a reorg while the index is deactivated")