Stabilize PPL ITs on the analytics-engine route (array/map-path/datatype/basic)

[ahkcs]

Description

Analytics-engine route (-Dtests.analytics.parquet_indices=true) parity pass across four PPL IT classes. All changes are test-only; the v2/Calcite route is unchanged (every gated test still runs there — the assumeNotAnalytics(...) guards are no-ops off-route and the gradle excludes apply only to integTestRemote).

CalciteArrayFunctionIT (43/60 → 44/60 pass, 16 excluded)

• array index load aborts init(): the array dataset's multi-value numbers field (scalar long mapping) can't be bulk-loaded into the parquet store. No test queries the array index (all build arrays inline via array(...)), so the load is skipped on the AE route.
• Higher-order lambda functions (transform/mvmap, reduce, filter, exists, forall) → No backend supports scalar function [...]. New ARRAY_HIGHER_ORDER_FUNC (16 tests).

CalcitePPLMapPathIT (25/27 → 25 pass, 2 excluded)

• mvcombine lowers to ARRAY_AGG, unregistered on the analytics backend → new MVCOMBINE_ARRAY_AGG.
• addtotals crashes the DataFusion backend with a join panic → new ADDTOTALS_JOIN_PANIC.

CalciteDataTypeIT (6 fail → excluded; guards added to base DataTypeIT)

• test_nonnumeric_data_types / test_alias_data_type: nested/object/geo/alias types stripped on the AE route (reuse NESTED_FIELDS). Also broadened the pre-existing org.opensearch.sql.ppl.* build.gradle globs to * so they cover the Calcite subclass (a latent gap — the old globs never matched CalciteDataTypeIT/CalciteSystemFunctionIT).
• test_numeric_data_types: scaled_float reported as bigint not double → new SCALED_FLOAT_TYPE.
• testNumericFieldFromString: empty-string → numeric coerces to null not 0 → new STRING_TO_NUMERIC_COERCION.
• testBooleanFieldFromNumberAcrossWildcardIndices: cross-index incompatible field types rejected → new CROSS_INDEX_INCOMPATIBLE_TYPES.
• testBooleanFieldFromString: seeds + deletes a doc; DELETE unsupported (DOC_MUTATION).

CalcitePPLBasicIT (1 fail → excluded)

• testRegexpFilter: the REGEXP filter throws a backend NullPointerException → new REGEXP_FILTER. (The rest of this class was already brought to parity in Bring CalcitePPLBasicIT to parity on the analytics-engine route #5542.)

Results (analytics route)

Test class	Before	After	v2/Calcite
CalciteArrayFunctionIT	43/60	44/60 pass, 16 excluded, 0 fail	60/60
CalcitePPLMapPathIT	25/27	25 pass, 2 excluded, 0 fail	27/27
CalciteDataTypeIT	1/7	1 run + 6 excluded, 0 fail	7/7
CalcitePPLBasicIT	45/46	45 run, 0 fail, 7 skip (pre-existing)	46/46

Check List

• New functionality includes testing.
• New functionality has been documented.
• Commits are signed per the DCO using --signoff.

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