ESQL: Use less data in test (#128337)

This test is expected to complete a deeply abusive lookup join without
circuit breaking. It was sometimes circuit breaking. This lowers the
data we feed to the test so its slightly less abusive. It's still plenty
abusive.

Closes #127365

Author: nik9000

muted-tests.yml

@@ -396,9 +396,6 @@ tests:
 - class: org.elasticsearch.xpack.remotecluster.CrossClusterEsqlRCS2EnrichUnavailableRemotesIT
   method: testEsqlEnrichWithSkipUnavailable
   issue: https://github.com/elastic/elasticsearch/issues/127368
-- class: org.elasticsearch.xpack.esql.heap_attack.HeapAttackIT
-  method: testLookupExplosionNoFetch
-  issue: https://github.com/elastic/elasticsearch/issues/127365
 - class: org.elasticsearch.xpack.test.rest.XPackRestIT
   method: test {p0=ml/data_frame_analytics_cat_apis/Test cat data frame analytics all jobs with header}
   issue: https://github.com/elastic/elasticsearch/issues/127625

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

@@ -655,7 +655,7 @@ public void testLookupExplosionManyMatches() throws IOException {
     }
 
     public void testLookupExplosionNoFetch() throws IOException {
-        int sensorDataCount = 7000;
+        int sensorDataCount = 6000;
         int lookupEntries = 10000;
         Map<?, ?> map = lookupExplosionNoFetch(sensorDataCount, lookupEntries);
         assertMap(map, matchesMap().extraOk().entry("values", List.of(List.of(sensorDataCount * lookupEntries))));