Merge bitcoin/bitcoin#24236: Remove utxo db upgrade code

fa9112aac0 Remove utxo db upgrade code (MarcoFalke)

Pull request description:

  It is not possible to upgrade Bitcoin Core pre-segwit (pre-0.13.1) to a recent version without a full IBD from scratch after  commit 19a56d1519 (released in version 22.0).

  Any Bitcoin Core version with the new database format after commit 1088b02f0c (released in version 0.15), can upgrade to any version that is supported as of today.

  This leaves the versions 0.13.1-0.14.x. Even though those versions are unsupported, some users with an existing datadir may want to upgrade to a recent version. However, it seems reasonable to simply ask them to `-reindex` to run a full IBD from scratch. This allows us to remove the utxo db upgrade code.

ACKs for top commit:
  Sjors:
    re-ACK fa9112aac0
  laanwj:
    Code review ACK fa9112aac0

Tree-SHA512: 4243bb35df9ac4892f9fad30fe486d338745952bcff4160bcb0937c772d57b13b800647da14695e21e3655e85ee0d95fa3dc7789ee309d59ad84f422297fecb8

test/functional/feature_unsupported_utxo_db.py

@@ -0,0 +1,61 @@
+#!/usr/bin/env python3
+# Copyright (c) 2022 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Test that unsupported utxo db causes an init error.
+
+Previous releases are required by this test, see test/README.md.
+"""
+
+import shutil
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import assert_equal
+
+
+class UnsupportedUtxoDbTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        self.num_nodes = 2
+
+    def skip_test_if_missing_module(self):
+        self.skip_if_no_previous_releases()
+
+    def setup_network(self):
+        self.add_nodes(
+            self.num_nodes,
+            versions=[
+                140300,  # Last release with previous utxo db format
+                None,  # For MiniWallet, without migration code
+            ],
+        )
+
+    def run_test(self):
+        self.log.info("Create previous version (v0.14.3) utxo db")
+        self.start_node(0)
+        block = self.generate(self.nodes[0], 1, sync_fun=self.no_op)[-1]
+        assert_equal(self.nodes[0].getbestblockhash(), block)
+        assert_equal(self.nodes[0].gettxoutsetinfo()["total_amount"], 50)
+        self.stop_nodes()
+
+        self.log.info("Check init error")
+        legacy_utxos_dir = self.nodes[0].chain_path / "chainstate"
+        legacy_blocks_dir = self.nodes[0].chain_path / "blocks"
+        recent_utxos_dir = self.nodes[1].chain_path / "chainstate"
+        recent_blocks_dir = self.nodes[1].chain_path / "blocks"
+        shutil.copytree(legacy_utxos_dir, recent_utxos_dir)
+        shutil.copytree(legacy_blocks_dir, recent_blocks_dir)
+        self.nodes[1].assert_start_raises_init_error(
+            expected_msg="Error: Unsupported chainstate database format found. "
+            "Please restart with -reindex-chainstate. "
+            "This will rebuild the chainstate database.",
+        )
+
+        self.log.info("Drop legacy utxo db")
+        self.start_node(1, extra_args=["-reindex-chainstate"])
+        assert_equal(self.nodes[1].getbestblockhash(), block)
+        assert_equal(self.nodes[1].gettxoutsetinfo()["total_amount"], 50)
+
+
+if __name__ == "__main__":
+    UnsupportedUtxoDbTest().main()

test/functional/test_runner.py

@@ -306,6 +306,7 @@ BASE_SCRIPTS = [
     'p2p_ping.py',
     'rpc_scantxoutset.py',
     'feature_txindex_compatibility.py',
+    'feature_unsupported_utxo_db.py',
     'feature_logging.py',
     'feature_anchors.py',
     'feature_coinstatsindex.py',