Stabilize CalcitePPLCaseFunctionIT on the analytics-engine route

Two test-infra issues caused 5 of the class's 6 analytics-route failures:
  - init() seeds four extra weblogs docs via unconditional raw PUTs
    (appendDataForBadResponse). init() runs as @before before every test method,
    and the analytics-engine parquet-backed store is append-only on same-_id PUT,
    so the docs accumulated a duplicate per method and inflated row counts across
    the suite. Guard the seeding on a pre-loadIndex isIndexExist check.
  - The otel_logs dataset has a multi-value attributes.email.invalid_recipients
    array, which the parquet/composite store rejects ('Cannot accept multiple
    values for field ... of type keyword'), aborting init() for every test. Only
    testNestedCaseAggWithAutoDateHistogram uses otel_logs, so skip the load on the
    analytics route.

The remaining failure is a genuine route divergence, skipped via the
assumeNotAnalytics(...) registry plus a matching excludeTestsMatching entry:
  - BIN_TIME_FIELD_BUCKETING: bin @timestamp then grouping by it returns the
    date-histogram bucket column typed string (not timestamp) on the AE route —
    testNestedCaseAggWithAutoDateHistogram.

Results (-Dtests.analytics.parquet_indices=true against the analytics route):
  CalcitePPLCaseFunctionIT: 3/9 -> 8/9 pass, 1 excluded, 0 fail
v2/Calcite route unchanged: 9/9 pass.

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

Author: ahkcs

integ-test/build.gradle

@@ -1164,6 +1164,14 @@ task integTestRemote(type: RestIntegTestTask) {
             //  - earliest('now', utc_timestamp()): 'now' and utc_timestamp() resolve to the same
             //    instant on the route (true) but differ on v2 (false).
             excludeTestsMatching '*CalcitePPLConditionBuiltinFunctionIT.testEarliestWithEval'
+
+            // === Excludes: CalcitePPLCaseFunctionIT route divergences ===
+            // The rest of the class passes once the weblogs raw-PUT seeding is guarded against
+            // append-only accumulation and the multi-value otel_logs dataset is skipped on the AE
+            // route (both in the IT's init()). This one carries an in-test assumeNotAnalytics(...).
+            //  - bin @timestamp then grouping by it returns the bucket column typed string (not
+            //    timestamp) on the AE route.
+            excludeTestsMatching '*CalcitePPLCaseFunctionIT.testNestedCaseAggWithAutoDateHistogram'
         }
     }
 

integ-test/src/test/java/org/opensearch/sql/calcite/remote/CalcitePPLCaseFunctionIT.java

@@ -5,10 +5,12 @@
 
 package org.opensearch.sql.calcite.remote;
 
+import static org.opensearch.sql.legacy.TestUtils.isIndexExist;
 import static org.opensearch.sql.legacy.TestsConstants.TEST_INDEX_BANK;
 import static org.opensearch.sql.legacy.TestsConstants.TEST_INDEX_OTEL_LOGS;
 import static org.opensearch.sql.legacy.TestsConstants.TEST_INDEX_STATE_COUNTRY_WITH_NULL;
 import static org.opensearch.sql.legacy.TestsConstants.TEST_INDEX_WEBLOGS;
+import static org.opensearch.sql.util.AnalyticsRouteLimitation.BIN_TIME_FIELD_BUCKETING;
 import static org.opensearch.sql.util.MatcherUtils.closeTo;
 import static org.opensearch.sql.util.MatcherUtils.rows;
 import static org.opensearch.sql.util.MatcherUtils.schema;
@@ -31,12 +33,25 @@ public void init() throws Exception {
     super.init();
     enableCalcite();
 
+    // init() runs as @Before, before every test method. On the analytics route the parquet-backed
+    // store is append-only on same-_id PUT, so seed the extra weblogs docs only when the index is
+    // first created — otherwise they accumulate a duplicate per test method and inflate row counts.
+    boolean weblogsExisted = isIndexExist(client(), TEST_INDEX_WEBLOGS);
     loadIndex(Index.WEBLOG);
     loadIndex(Index.TIME_TEST_DATA);
     loadIndex(Index.STATE_COUNTRY_WITH_NULL);
     loadIndex(Index.BANK);
-    loadIndex(Index.OTELLOGS);
-    appendDataForBadResponse();
+    // The otel_logs dataset has a multi-value attributes.email.invalid_recipients array, which the
+    // parquet/composite store rejects ("Cannot accept multiple values for field ... of type
+    // keyword"), aborting init() for every test. Only testNestedCaseAggWithAutoDateHistogram uses
+    // this index and it is skipped on the analytics route (BIN_TIME_FIELD_BUCKETING), so skip the
+    // load there.
+    if (!isAnalyticsParquetIndicesEnabled()) {
+      loadIndex(Index.OTELLOGS);
+    }
+    if (!weblogsExisted) {
+      appendDataForBadResponse();
+    }
   }
 
   private void appendDataForBadResponse() throws IOException {
@@ -484,6 +499,9 @@ public void testNestedCaseAggWithAutoDateHistogram() throws IOException {
         "The query cannot be executed when pushdown is disabled due to implementation defects of"
             + " the bin command",
         isPushdownDisabled());
+    // bin @timestamp then grouping by it returns the bucket column typed string (not timestamp) on
+    // the analytics route; the query also reads otel_logs, which isn't loaded on that route.
+    assumeNotAnalytics(BIN_TIME_FIELD_BUCKETING);
     JSONObject actual1 =
         executeQuery(
             String.format(