assumeutxo: Drop block height from metadata

The Snapshot format version is updated to 2 to indicate this change.

Co-authored-by: MarcoFalke <*~=`'#}+{/-|&$^_@721217.xyz>

test/functional/rpc_dumptxoutset.py

@@ -43,7 +43,7 @@ class DumptxoutsetTest(BitcoinTestFramework):
         # UTXO snapshot hash should be deterministic based on mocked time.
         assert_equal(
             sha256sum_file(str(expected_path)).hex(),
-            '2f775f82811150d310527b5ff773f81fb0fb517e941c543c1f7c4d38fd2717b3')
+            '31fcdd0cf542a4b1dfc13c3c05106620ce48951ef62907dd8e5e8c15a0aa993b')
 
         assert_equal(
             out['txoutset_hash'], 'a0b7baa3bf5ccbd3279728f230d7ca0c44a76e9923fca8f32dbfd08d65ea496a')