Merge bitcoin/bitcoin#30340: test: Added coverage to Block not found error using gettxoutsetinfo

8ec24bd test: Added coverage to Block not found error using gettxoutsetinfo (kevkevinpal)

Pull request description:

  #### Description
  There were no tests that checked for the `Block not found` error called in `ParseHashOrHeight` when using `gettxoutsetinfo`, this change adds coverage to it.

  You can see there are no tests that do the following by doing the below
  `grep -nri "Block not found.*gettxoutsetinfo" ./test/functional/`

  which leads to no results

ACKs for top commit:
  achow101:
    ACK 8ec24bd
  tdb3:
    ACK 8ec24bd
  kristapsk:
    ACK 8ec24bd
  brunoerg:
    crACK 8ec24bd
  alfonsoromanz:
    Re ACK 8ec24bd

Tree-SHA512: 2c61c681e7304c679cc3d7dd13af1b795780e85716c25c7423d68104e253d01271e048e21bc21be35dbc7ec1a4fde94e439542f3cfd669fe5a16478c5fa982ab

Author: achow101

test/functional/feature_coinstatsindex.py

@@ -242,6 +242,9 @@ def _test_coin_stats_index(self):
         res12 = index_node.gettxoutsetinfo('muhash')
         assert_equal(res12, res10)
 
+        self.log.info("Test obtaining info for a non-existent block hash")
+        assert_raises_rpc_error(-5, "Block not found", index_node.gettxoutsetinfo, hash_type="none", hash_or_height="ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", use_index=True)
+
     def _test_use_index_option(self):
         self.log.info("Test use_index option for nodes running the index")