[GLUTEN-11916][VL][TEST] Enable subquery/exists-subquery/exists-orderby-limit.sql with SPARK-57125 workaround

[rdtr]

Summary

Enables subquery/exists-subquery/exists-orderby-limit.sql in spark41 SQL query tests by re-enabling ConstantFolding for just this one file via a per-file --SET spark.sql.optimizer.excludedRules=... directive. The test was previously TODO-commented out because it crashed with an INTERNAL_ERROR during physical planning.

Root cause

GlutenSQLQueryTestSuite excludes ConvertToLocalRelation, ConstantFolding,
and NullPropagation from the optimizer by default to force queries through
Gluten's offload paths. With ConstantFolding excluded, Spark's LimitPushDown
rule produces an unfolded Add expression that BasicOperators in
SparkStrategies cannot match, causing physical planning to fail with:

java.lang.AssertionError: assertion failed: No plan for LocalLimit (1 + 2)
+- Project [1 AS col#...]
   +- Filter (dept_id#... > 10)
      +- LocalRelation [dept_id#..., dept_name#..., state#...]

  at scala.Predef$.assert(Predef.scala:279)
  at org.apache.spark.sql.catalyst.planning.QueryPlanner.plan(QueryPlanner.scala:93)
  at org.apache.spark.sql.execution.SparkStrategies.plan(SparkStrategies.scala:79)
  ...
  at org.apache.spark.sql.execution.adaptive.InsertAdaptiveSparkPlan.compileSubquery(...)

wrapped as [INTERNAL_ERROR] The Spark SQL phase planning failed with an internal error.

The trigger is the EXISTS+OFFSET pattern (query # 17 in this SQL file):

SELECT * FROM emp WHERE EXISTS (
  SELECT dept.dept_name FROM dept WHERE dept.dept_id > 10 LIMIT 1 OFFSET 2
)

LimitPushDown rewrites LocalLimit(le, Offset(oe, child)) into Offset(oe, LocalLimit(Add(le, oe), child)) and relies on ConstantFolding to subsequently fold Add(Literal(1), Literal(2)) to Literal(3) so that BasicOperators (which only matches LocalLimit(IntegerLiteral, _)) can produce a physical plan.

Fix

Add a per-file --SET directive that overrides the default exclusion to only exclude ConvertToLocalRelation, re-enabling ConstantFolding (and NullPropagation, which gets re-enabled because the test framework's --SET parser splits values by comma — see the note below). This keeps Gluten's offload paths exercised while allowing the test to plan.

The upstream Spark fix is tracked as SPARK-57125 (PR
apache/spark#56180), which makes
LimitPushDown produce a folded literal directly so the rule no longer depends
on ConstantFolding. Once that lands and Gluten picks up the Spark version,
the --SET directive in this file can be removed.

Test framework limitation

The Gluten/Spark SQL test framework's --SET parser at
SQLQueryTestHelper.scala:476-481 splits values by comma at the top level,
which means multi-rule values like
excludedRules=Rule1,Rule2 can't be specified in a single --SET
(StringIndexOutOfBoundsException). For now, accepting NullPropagation
being re-enabled is fine for this test. Filed as a separate follow-up.

Verification

• ✅ Reproduced the AssertionError: No plan for LocalLimit (1 + 2) by
  enabling the test without the --SET directive on the original
  GlutenSQLQueryTestSuite (not a diagnostic subclass).
• ✅ With the --SET directive applied, the test passes.
• ✅ Spark unit test added in SPARK-57125 / [SPARK-57125][SQL] LimitPushDown should fold literal Limit+Offset sum so plan stays planable without ConstantFolding spark#56180 fails on
  master and passes with the upstream fix.

Regarding Spark 4.0

The same SQL test file (with the same EXISTS+OFFSET queries) is enabled and
appears to pass in gluten-ut/spark40. I checked:

• Same SQL input file content
• Identical golden file (both versions expect successful results for the
  OFFSET queries)
• Same LimitPushDown rule in Spark 4.0.0 source (verified via the GitHub
  v4.0.0 tag)
• Same BasicOperators IntegerLiteral-only matchers in Spark 4.0.0 source
• Same rule exclusions (ConvertToLocalRelation, ConstantFolding,
  NullPropagation) in gluten-ut/spark40/.../GlutenSQLQueryTestSuite.scala
• gluten-ut/spark40 is enabled in velox_backend_x86.yml and the
  spark-test-spark40-slow job runs GlutenSQLQueryTestSuite via the
  ExtendedSQLTest tag — and passes

I couldn't identify what makes Spark 4.0.0 + Gluten avoid hitting this code path while Spark 4.1.1 + Gluten triggers it. The bug ingredients look identical. If a reviewer with more context on the spark40 setup can shed light, that would be appreciated — but it doesn't block this PR. I am happy to build and test locally with 4.0 if necessary.

Test plan

• CI: spark-test-spark41-slow runs GlutenSQLQueryTestSuite with
  ExtendedSQLTest tag, which exercises this file.
• Verified locally in IntelliJ by running GlutenSQLQueryTestSuite
  filtered to subquery/exists-subquery/exists-orderby-limit.sql.

Related: GLUTEN-11916, #12146
(first batch of Spark 4.1 TODO test fixes).

Related issue: #11916