ESQL: Fewer serverless docs in tests (elastic#131651)

Drops the number of docs per bulk in test using 5mb text fields for
serverless. And raises the number in stateful. Not sure what's up,
sending it to the serverless friends to dig more. But this should make
it stable in the mean time.

Author: nik9000

test/external-modules/esql-heap-attack/src/javaRestTest/java/org/elasticsearch/xpack/esql/heap_attack/HeapAttackIT.java

@@ -884,8 +884,19 @@ private void initManyBigFieldsIndex(int docs, String type) throws IOException {
     }
 
     private void initGiantTextField(int docs) throws IOException {
-        logger.info("loading many documents with one big text field");
-        int docsPerBulk = 3;
+        int docsPerBulk = 10;
+        for (Map<?, ?> nodeInfo : getNodesInfo(adminClient()).values()) {
+            for (Object module : (List<?>) nodeInfo.get("modules")) {
+                Map<?, ?> moduleInfo = (Map<?, ?>) module;
+                final String moduleName = moduleInfo.get("name").toString();
+                if (moduleName.startsWith("serverless-")) {
+                    docsPerBulk = 3;
+                }
+            }
+        }
+
+        logger.info("loading many documents with one big text field - docs per bulk {}", docsPerBulk);
+
         int fieldSize = Math.toIntExact(ByteSizeValue.ofMb(5).getBytes());
 
         Request request = new Request("PUT", "/bigtext");
@@ -912,6 +923,7 @@ private void initGiantTextField(int docs) throws IOException {
             }
         }
         initIndex("bigtext", bulk.toString());
+        logger.info("loaded");
     }
 
     private void initMvLongsIndex(int docs, int fields, int fieldValues) throws IOException {