Merge bitcoin/bitcoin#28195: blockstorage: Drop legacy -txindex check

fae405556d scripted-diff: Rename CBlockTreeDB -> BlockTreeDB (MarcoFalke)
faf63039cc Fixup style of moved code (MarcoFalke)
fa65111b99 move-only: Move CBlockTreeDB to node/blockstorage (MarcoFalke)
fa8685597e index: Drop legacy -txindex check (MarcoFalke)
fa69148a0a scripted-diff: Use blocks_path where possible (MarcoFalke)

Pull request description:

  The only reason for the check was to print a warning about an increase in storage use. Now that 22.x is EOL and everyone should have migrated (or decided to not care about storage use), remove the check.

  Also, a move-only commit is included. (Rebased from https://github.com/bitcoin/bitcoin/pull/22242)

ACKs for top commit:
  TheCharlatan:
    ACK fae405556d, though I lack historical context to really judge the second commit fa8685597e.
  stickies-v:
    ACK fae405556d

Tree-SHA512: 9da8f48767ae52d8e8e21c09a40c949cc0838794f1856cc5f58a91acd3f00a3bca818c8082242b3fdc9ca5badb09059570bb3870850d3807b75a8e23b5222da1

src/test/util/setup_common.cpp

@@ -64,6 +64,7 @@
 #include <functional>
 #include <stdexcept>
 
+using kernel::BlockTreeDB;
 using kernel::ValidationCacheSizes;
 using node::ApplyArgsManOptions;
 using node::BlockAssembler;
@@ -182,7 +183,7 @@ ChainTestingSetup::ChainTestingSetup(const ChainType chainType, const std::vecto
         .notifications = chainman_opts.notifications,
     };
     m_node.chainman = std::make_unique<ChainstateManager>(m_node.kernel->interrupt, chainman_opts, blockman_opts);
-    m_node.chainman->m_blockman.m_block_tree_db = std::make_unique<CBlockTreeDB>(DBParams{
+    m_node.chainman->m_blockman.m_block_tree_db = std::make_unique<BlockTreeDB>(DBParams{
         .path = m_args.GetDataDirNet() / "blocks" / "index",
         .cache_bytes = static_cast<size_t>(m_cache_sizes.block_tree_db),
         .memory_only = true});