Version bump to OpenSearch 3.7 with async QueryPlanExecutor (opensearch-project#5396)

* Version bump to OpenSearch 3.7 (Jackson 2 → 3 parser API + _source excludes serialization) (opensearch-project#5361)

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

* Update vendored analytics JARs from 3.6 to 3.7

Replace libs/ JARs with 3.7.0-SNAPSHOT versions built from the
OpenSearch sandbox. Update build files to reference 3.7 file names.
Keep files() references instead of Maven coordinates so CI can
resolve dependencies without publishToMavenLocal.

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

* Async QueryPlanExecutor + drop stub and stub-only ITs

The analytics-framework 3.7 QueryPlanExecutor interface is async
(void execute(plan, ctx, ActionListener<Stream>)). Update
AnalyticsExecutionEngine to dispatch via the listener instead of the
old synchronous return-value form, and rework the unit test mocks
likewise.

Drop StubQueryPlanExecutor and its callers (TransportPPLQueryAction,
SQLPlugin, RestUnifiedQueryActionTest); the SQL plugin now expects
the real analytics-engine executor to be supplied via Guice
cross-plugin injection (a small AnalyticsExecutorHolder bridges the
binding to the SQLPlugin REST handler that runs before Node injection).

Drop AnalyticsPPLIT and AnalyticsExplainIT (and their
expectedOutput/analytics fixtures): these tested stub canned data
which no longer exists.

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

---------

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

Author: ahkcs

build.gradle

@@ -127,6 +127,11 @@ allprojects {
         version += "-SNAPSHOT"
     }
 
+    // Path to the analytics-engine plugin ZIP. Override with
+    // `-PanalyticsEngineZip=/path/to/zip` if needed.
+    ext.analyticsEngineZip = project.findProperty('analyticsEngineZip') ?:
+            "${rootDir}/libs/analytics-engine-3.7.0-SNAPSHOT.zip"
+
     plugins.withId('java') {
         java {
             sourceCompatibility = JavaVersion.VERSION_21

doctest/build.gradle

@@ -195,7 +195,7 @@ testClusters {
         }))
         */
         plugin(getJobSchedulerPlugin(jsPlugin, bwcOpenSearchJSDownload))
-        plugin provider { (RegularFile) (() -> file("${rootDir}/libs/analytics-engine-3.6.0-SNAPSHOT.zip")) }
+        plugin provider { (RegularFile) (() -> file("${rootDir}/libs/analytics-engine-3.7.0-SNAPSHOT.zip")) }
         plugin ':opensearch-sql-plugin'
         testDistribution = 'archive'
     }