Bump Gradle wrapper from 9.2.0 to 9.4.1 to satisfy the minimum version
required by opensearch-build-tools 3.7.0-SNAPSHOT (GlobalBuildInfoPlugin).

Exclude 24 @Ignore-annotated test classes from integTest at the Gradle
layer to work around a Gradle 9.4.1+ bug where
TestEventReporterAsListener crashes with ClassCastException when
encountering class-level @ignore annotations. These classes were already
skipped by JUnit; this moves the skip earlier to avoid the buggy bridge.
Not fixed as of Gradle 9.5.0.

Refs: opensearch-project/OpenSearch#21153, opensearch-project#5406
Signed-off-by: Chen Dai <daichen@amazon.com>

Mirrors the trailing portion of #5414 onto
feature/mustang-ppl-integration. The Gradle 9.4.1 wrapper bump (#5406)
and the integTest exclude block for @ignore'd classes (#5407) already
landed on this branch, but the matching cleanup of `CalciteNoPushdownIT`
did not — the @suite still listed four classes that are now build-time
excluded from integTest:

  - CalciteInformationSchemaCommandIT
  - CalciteJsonFunctionsIT
  - CalcitePrometheusDataSourceCommandsIT
  - CalciteShowDataSourcesCommandIT

Leaving them in the suite means the JUnit runner attempts to load each
class, finds it referenced from the suite, and registers a descriptor —
which (combined with the class-level @ignore) reproduces the same
TestEventReporterAsListener.started cast that the integTest exclude was
meant to avoid. Dropping the entries here keeps the no-pushdown suite
consistent with the exclude block: a class excluded at the build layer
must not also appear in any @Suite.SuiteClasses list.

No new tests are introduced or removed — the four classes are already
@ignore'd and have been since they were written. This change is purely
about keeping the no-pushdown suite metadata aligned with the exclusion
pattern carried over from main.

Signed-off-by: Kai Huang <ahkcs@amazon.com>

…ation

Brings the catch-up branch up to current upstream/main (4 commits since
this PR was opened) and current feature/mustang-ppl-integration (9
commits since this PR was opened), so the PR is mergeable into
feature/mustang-ppl-integration without conflicts.

Squashed (rather than two real merge commits) for the same DCO reason
the original commit was squashed: upstream commits authored by many
contributors with inconsistent or missing Signed-off-by trailers would
otherwise be brought into this PR's history.

Newer main commits absorbed (4):
- opensearch-project#5419 (LENGTH/REGEXP_REPLACE/DATE_TRUNC unified function spec)
- opensearch-project#5408 (datetime type normalization)
- opensearch-project#5414 (Gradle wrapper bump + @ignore exclusion)
- opensearch-project#5399 (FGAC-scoped SQL cursor continuation)

Newer feature commits absorbed (9):
- opensearch-project#5403 (analytics-engine optional dependency — major rewiring)
- opensearch-project#5407 (Carry CalciteEvalCommandIT through helper-managed index path)
- opensearch-project#5413 (Default plugins.calcite.enabled=true on unified path)
- opensearch-project#5415, opensearch-project#5416, opensearch-project#5417, opensearch-project#5409, opensearch-project#5400, opensearch-project#5406 (smaller carryovers + bumps)

Conflict resolutions (10 from main side, 3 from feature side):

api/spec/* (LanguageSpec, UnifiedFunctionSpec, UnifiedPplSpec,
UnifiedSqlSpec): took main. Main is a strict superset — adds
postAnalysisRules and preCompilationRules extension points, the new
FunctionSpecBuilder DSL, SCALAR category for length/regexp_replace/
date_trunc, the DatetimeExtension on PPL spec, and the CoreExtension
wiring on SQL spec. PR's RELEVANCE category is preserved unchanged.

api/UnifiedQueryPlanner.java, api/compiler/UnifiedQueryCompiler.java:
took main. Both adopt the new postAnalysisRules / preCompilationRules
hooks introduced in opensearch-project#5408 / opensearch-project#5419.

core/executor/QueryService.java: composed both sides — kept HEAD's
CalciteClassLoaderHelper.withCalciteClassLoader wrapper around main's
StageErrorHandler stage tracking. Same pattern as the original PR
resolution; both improvements are orthogonal.

legacy/plugin/RestSqlAction.java: took HEAD. The 3-way merge produced
a duplicated handleException/getRawErrorCode block; HEAD already
contained both the delegateToV2Engine refactor and the ErrorReport
unwrap from main, so HEAD is the correct superset.

integ-test/build.gradle: took feature. Both sides added the same
@ignore exclusion block; feature has alphabetical ordering and a more
detailed comment explaining the Gradle 9.4.1 TestEventReporterAsListener
cast bug.

integ-test/.../CalciteEvalCommandIT.java: composed both sides. Took
feature's helper-managed test_eval provisioning (createIndexByRestClient
+ isIndexExist guard, from opensearch-project#5407) so analytics-engine compatibility runs
get a parquet-backed index. Added back PR HEAD's test_eval_agent setup
(needed by the dotted-path eval tests for opensearch-project#5351) wrapped in its own
isIndexExist guard for the same parquet-aware idempotency.

plugin/.../TransportPPLQueryAction.java: took feature. PR opensearch-project#5403 made
analytics-engine an optional dependency by moving QueryPlanExecutor
from a required constructor parameter to an @Inject(optional=true)
setter. Feature's design supersedes our prior wiring.

plugin/.../SQLPlugin.java: took feature. The same opensearch-project#5403 simplification
removed loadExtensions/EngineExtensionsHolder/executionEngineExtensions
plumbing (no longer needed once analytics-engine is optionally bound).
Feature retains the createSqlAnalyticsRouter method this PR introduced.

plugin/.../config/EngineExtensionsHolder.java: deleted. Unreferenced
after taking feature's SQLPlugin/TransportPPLQueryAction; not present
on feature branch.

Build: :api, :core, :opensearch-sql-plugin, :legacy compileJava +
:integ-test compileTestJava all pass; unit tests pass; spotlessCheck
clean.

Signed-off-by: Kai Huang <ahkcs@amazon.com>