ESQL: Weaken test assertion (#114336) (#114351)

Weaken the assertion when testing breakers: it's ok to break while
building a block in addition to topn.

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

@@ -166,7 +166,7 @@ public class HeapAttackIT extends ESRestTestCase {
                     "error",
                     matchesMap().extraOk()
                         .entry("bytes_wanted", greaterThan(1000))
-                        .entry("reason", matchesRegex("\\[request] Data too large, data for \\[topn] would .+"))
+                        .entry("reason", matchesRegex("\\[request] Data too large, data for \\[(topn|esql_block_factory)] would .+"))
                         .entry("durability", "TRANSIENT")
                         .entry("type", "circuit_breaking_exception")
                         .entry("bytes_limit", greaterThan(1000))