fix(reader): honour bloom_filter_on_read

[anoop-narang]

The liquid parquet reader ignores datafusion.execution.parquet.bloom_filter_on_read. Whenever a scan has a pruning predicate, it loads and applies every remaining row group's bloom filters, even with the option set to false.

let config = SessionConfig::new()
    .set_bool("datafusion.execution.parquet.bloom_filter_on_read", false);
let ctx = SessionContext::new_with_config(config);
// register a parquet table `t` with bloom filters, then:
// SELECT * FROM t WHERE a = 2

With ParquetSource, this scan reads no bloom filters. Once the scan goes through LiquidParquetSource, it reads them anyway, and row_groups_pruned_bloom_filter reports row groups pruned by a filter the session turned off.

Why it matters

Each bloom filter is a separate ranged read per row group and predicate column, and the reads are not cached across queries. Callers turn the option off when bloom checks cannot pay for themselves — for example, many small files where file-level pruning has already selected exactly the files that match. Today they have no way to avoid those reads.

The option was honoured in the original opener and dropped in d7f0741 ("remove some flags"). If leaving it out was deliberate, I'm happy to hear the reasoning; otherwise this restores it.

The fix

LiquidParquetSource already carries the session's TableParquetOptions. Pass global.bloom_filter_on_read into the morselizer and skip the bloom-filter load when it is off. As in DataFusion's own opener, the remaining row groups are then counted as matched by bloom filters, so the pruning metrics stay consistent between the two sources.

Tests

The existing prunes_row_group_with_bloom_filter test becomes a helper parameterised on the option, and a new test covers the off case:

• prunes_row_group_with_bloom_filter (on): 1 row, 1 row group pruned, 1 matched.
• skips_bloom_filter_when_bloom_filter_on_read_is_off (off): 1 row, 0 pruned, 2 matched. The predicate alone still produces the right answer.

With the test applied to main and the fix left out:

$ cargo test -p liquid-cache-datafusion --lib bloom

test optimizers::tests::prunes_row_group_with_bloom_filter ... ok
test optimizers::tests::skips_bloom_filter_when_bloom_filter_on_read_is_off ... FAILED
assertion `left == right` failed
  left: 1
 right: 0

With the fix, cargo test -p liquid-cache-datafusion passes (63 tests).

[codecov-commenter]

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