Ensure only parent breaker trips in unit test

With this commit we raise the limit of the child circuit breaker used in
the unit test for the circuit breaker service so it is high enough to trip
only the parent circuit breaker. The previous limit was 300 bytes but
theoretically (considering overhead) we could reach 346 bytes. Thus any
value larger than 300 bytes could trip the child circuit breaker leading
to spurious failures.

Relates #31767

server/src/test/java/org/elasticsearch/indices/breaker/HierarchyCircuitBreakerServiceTests.java

@@ -206,7 +206,7 @@ public void testParentBreaksOnRealMemoryUsage() throws Exception {
         Settings clusterSettings = Settings.builder()
             .put(HierarchyCircuitBreakerService.USE_REAL_MEMORY_USAGE_SETTING.getKey(), Boolean.TRUE)
             .put(HierarchyCircuitBreakerService.TOTAL_CIRCUIT_BREAKER_LIMIT_SETTING.getKey(), "200b")
-            .put(HierarchyCircuitBreakerService.REQUEST_CIRCUIT_BREAKER_LIMIT_SETTING.getKey(), "300b")
+            .put(HierarchyCircuitBreakerService.REQUEST_CIRCUIT_BREAKER_LIMIT_SETTING.getKey(), "350b")
             .put(HierarchyCircuitBreakerService.REQUEST_CIRCUIT_BREAKER_OVERHEAD_SETTING.getKey(), 2)
             .build();