fix: dedup commutative AND/OR operands when canonicalize is disabled

[1fanwang]

Which issue does this PR close?

• Closes Expr simplifier doesn't simplify exprs that are same if you swap lhs with rhs regardless of cycles #14943.

Revives #21870, which was closed by the stale bot. The direction was agreed with @asolimando and sql_planner was benchmarked by @alamb there (results, no measurable change).

Rationale for this change

SimplifyExpressions disables canonicalization for LogicalPlan::Join (see #8780), so the AND/OR dedup in expr_contains_inner — which compares each conjunct/disjunct leaf with structural == — cannot recognize duplicates that differ only by commutative operand order (A = B vs B = A). Simplifying inside a join filter (the delta-rs MERGE case reported in #14943) keeps the duplicate across simplifier cycles because nothing normalizes operand order first.

@alamb pointed at the fix in the issue thread: CSE already dedups A = B / B = A via NormalizeEq; route the simplifier's leaf comparison through the same trait.

What changes are included in this PR?

expr_contains_inner compares leaves with Expr::normalize_eq instead of ==. NormalizeEq handles +, *, &, |, ^, =, != commutatively and falls back to structural == for everything else, so non-commutative rules and the existing !needle.is_volatile() guard are unchanged. A regression test covers the AND, OR, and 3-conjunct nested forms.

Are these changes tested?

Yes. The new test_simplify_swapped_operands_in_and_or_no_canonicalize fails on main (the duplicate passes through unchanged) and passes with the fix. The full datafusion-optimizer lib suite and cargo clippy are clean, and the sql_planner benchmark linked above shows no measurable change.

Are there any user-facing changes?

No public API changes. AND/OR chains containing commutative-equivalent duplicates now collapse even when the simplifier's canonicalizer is disabled (currently the LogicalPlan::Join path). Canonicalize-on paths produce the same output as before.

[alamb]

Thank you @1fanwang

[alamb]

I took the liberty of adding some slt coverage for this feature too

[alamb]

These fail like this on main

warning: `datafusion-sqllogictest` (test "sqllogictests") generated 1 warning
    Finished `ci` profile [unoptimized] target(s) in 1m 45s
     Running bin/sqllogictests.rs (target/ci/deps/sqllogictests-01bd002bb437dcb6)
Running with 16 test threads (available parallelism: 16)
Completed 493 test files in 6 seconds                                                                                          External error: 2 errors in file /Users/andrewlamb/Software/datafusion/datafusion/sqllogictest/test_files/simplify_expr.slt

1. query result mismatch:
[SQL] explain select * from t1 join t2 on t1.a = t2.b or t2.b = t1.a;
[Diff] (-expected|+actual)
    logical_plan
-   01)Inner Join: t1.a = t2.b
+   01)Inner Join:  Filter: t1.a = t2.b OR t2.b = t1.a
    02)--TableScan: t1 projection=[a]
    03)--TableScan: t2 projection=[b]
    physical_plan
-   01)HashJoinExec: mode=CollectLeft, join_type=Inner, on=[(a@0, b@0)]
+   01)NestedLoopJoinExec: join_type=Inner, filter=a@0 = b@1 OR b@1 = a@0
    02)--DataSourceExec: partitions=1, partition_sizes=[1]
    03)--DataSourceExec: partitions=1, partition_sizes=[1]
at /Users/andrewlamb/Software/datafusion/datafusion/sqllogictest/test_files/simplify_expr.slt:162


2. query result mismatch:
[SQL] explain select * from t1 join t2 on t1.a > t2.b and (t1.a + t2.b > 1 or t2.b + t1.a > 1);
[Diff] (-expected|+actual)
    logical_plan
-   01)Inner Join:  Filter: t1.a > t2.b AND t1.a + t2.b > Int32(1)
+   01)Inner Join:  Filter: t1.a > t2.b AND (t1.a + t2.b > Int32(1) OR t2.b + t1.a > Int32(1))
    02)--TableScan: t1 projection=[a]
    03)--TableScan: t2 projection=[b]
    physical_plan
-   01)NestedLoopJoinExec: join_type=Inner, filter=a@0 > b@1 AND a@0 + b@1 > 1
+   01)NestedLoopJoinExec: join_type=Inner, filter=a@0 > b@1 AND (a@0 + b@1 > 1 OR b@1 + a@0 > 1)
    02)--DataSourceExec: partitions=1, partition_sizes=[1]
    03)--DataSourceExec: partitions=1, partition_sizes=[1]
at /Users/andrewlamb/Software/datafusion/datafusion/sqllogictest/test_files/simplify_expr.slt:181

[1fanwang]

Thanks a lot @alamb checking now