[core] Negate predicates like Java so NULL rows stay excluded

[JeonDaehong]

Purpose

Linked issue: close #1143

Predicate::negate wrapped leaves in Not, and Not was evaluated as !inner, so a NULL input made NOT(p = 'a') true. Reads returned those rows and delete_by_predicate deleted them. Java flips the leaf instead (Equal.negate() is NotEqual), which is false for NULL.

Brief change log

• Predicate::negate now does what Java Predicate.negate does: flip the leaf operator (=/!=, </>=, <=/>, IS NULL/IS NOT NULL, IN/NOT IN, BETWEEN/NOT BETWEEN) and push through AND/OR with De Morgan.
• DataFusion: the NOT BETWEEN coverage check in scan.rs now matches the new shape of the negated filter (x < lo OR x > hi instead of NOT(x >= lo AND x <= hi)).
• Leaves with no negated operator here (STARTS_WITH, ENDS_WITH, CONTAINS, LIKE, array ops) stay as Not(leaf). eval_row and the residual row filter now return false for those when the input is NULL, same as Java NotStartsWith/NotLike/... .

Tests

• negated_predicates_keep_null_rows and negated_data_predicate_keeps_null_rows cover the cases from the issue on the partition and DV delete paths and on reads. Both fail on main.
• Unit tests for negate and for NULL evaluation in eval_row and the residual filter.
• Changed existing tests:
  • test_file_index_nested_not_with_added_column_falls_back now expects [1] instead of [1, 2]. added is NULL in the old file, so for id 2 the predicate is NOT(true AND unknown). Java drops that row too.
  • test_not / test_display_not, three DataFusion pushdown tests, the global index exactness test and the stats fail-open test asserted the old Not shape. The last two now build Predicate::Not directly so they keep testing the Not branch.

fmt and clippy (1.98.0, -D warnings) pass. cargo test --no-fail-fast -p paimon -p paimon-datafusion -p paimon-c: 5804 passed. The 39 failures are all TableNotExist / table not found for the fixture tables CI provisions, plus 2 that need the lumina library. The ones I checked fail the same way on main.

Not covered here: a Predicate::Not around AND/OR built by hand (not through negate) is still evaluated as !inner. Nothing in core builds that today, but I can add it if you'd like.

API and Format

No API change. Predicate::negate returns a different but equivalent tree for non-NULL inputs.

Documentation

None.

[JeonDaehong]

@JingsongLi @leaves12138 could you take a look when you have time? Fixes #1143: delete_by_predicate with a negated predicate was also deleting rows where the column is NULL.

[JeonDaehong]

Moved to draft until CI is green. I couldn't run the docker fixtures and the Go/Python suites locally. Will mark it ready once they pass.

[JeonDaehong]

CI is green, ready for review.