ESQL: Grow heap attack tests (elastic#121714)

This causes the ESQL heap attack tests to grow their memory usage if
they first don't cause a circuit breaking exception. It just tries again
with more data. That's slow, but it should stop this from failing quite
as much. And it'll give us even more information about failures.

Closes elastic#121465

Author: nik9000

muted-tests.yml

@@ -524,9 +524,6 @@ tests:
 - class: org.elasticsearch.xpack.ml.packageloader.action.ModelLoaderUtilsTests
   method: testSplitIntoRanges
   issue: https://github.com/elastic/elasticsearch/issues/121799
-- class: org.elasticsearch.xpack.esql.heap_attack.HeapAttackIT
-  method: testLookupExplosionBigStringManyMatches
-  issue: https://github.com/elastic/elasticsearch/issues/121465
 - class: org.elasticsearch.search.fetch.subphase.highlight.HighlightBuilderTests
   method: testInvalidMaxAnalyzedOffset
   issue: https://github.com/elastic/elasticsearch/issues/121361