txospenderindex: disable bloom filters to optimize disk usage #35568

LevelDB bloom filters are only consulted on Get point reads. This can be verified in https://github.com/bitcoin/bitcoin/blob/master/src/leveldb/table/table.cc#L224-L228. InternalGet is the only place that consults the filter, and it is only reached via a Get or Exists point read. The filters are never consulted for iterator seeks with an iterator created via NewIterator. txospenderindex only reads via iterator seeks, so building them is wasted effort and space.

For a db as large as txospenderindex, this results in measurable performance and disk usage. On master, a full sync took 2h46m, and the resulting db was 94.5 GB. On this branch, a full sync took 2h32m, and the resulting db was 90 GB. So this is a sync speedup of 14 minutes, and a disk space reduction of 4.5 GB.

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Code Coverage & Benchmarks

For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/35568.

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Conflicts

Reviewers, this pull request conflicts with the following ones:

• #35531 (txindex: use 5-byte siphash keys to optimize disk usage by andrewtoth)
• #34132 (coins: drop error catcher, centralize fatal read handling by l0rinc)
• #33324 (blocks: add -reobfuscate-blocks argument to enable (de)obfuscating existing blocks by l0rinc)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

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Nice find, ACK 74dfc8ec49c7bb480dac0c785cc2aae1a5e3ca30