[validation] Make script error messages uniform for parallel/single validation

This makes the debug output mostly the same for -par=1 and parallel validation runs. Of course,
parallel validation is non-deterministic in what error it may encounter first if there are
multiple issues. Also, the way certain script-related and non-script-related checks are
performed differs between the two modes still, which may result in discrepancies.

test/functional/feature_cltv.py

@@ -87,7 +87,6 @@ class BIP65Test(BitcoinTestFramework):
         self.noban_tx_relay = True
         self.extra_args = [[
             f'-testactivationheight=cltv@{CLTV_HEIGHT}',
-            '-par=1',  # Use only one script thread to get the exact reject reason for testing
             '-acceptnonstdtxn=1',  # cltv_invalidate is nonstandard
         ]]
         self.setup_clean_chain = True
@@ -175,7 +174,7 @@ class BIP65Test(BitcoinTestFramework):
             block.hashMerkleRoot = block.calc_merkle_root()
             block.solve()
 
-            with self.nodes[0].assert_debug_log(expected_msgs=[f'CheckInputScripts on {block.vtx[-1].hash} failed with {expected_cltv_reject_reason}']):
+            with self.nodes[0].assert_debug_log(expected_msgs=[f'Script validation error in block: {expected_cltv_reject_reason}']):
                 peer.send_and_ping(msg_block(block))
                 assert_equal(int(self.nodes[0].getbestblockhash(), 16), tip)
                 peer.sync_with_ping()