Fix scaling thread pool test bug

This commit adjusts the expectation for the max number of threads in the
scaling thread pool configuration test. The reason that this expectation
is incorrect is because we removed the limitation that the number of
processors maxes out at 32, instead letting it be the true number of
logical processors on the machine. However, when we removed this
limitation, this test was never adjusted to reflect the new reality yet
it never arose since our tests were not running on machines with
incredibly high core counts.

Relates #20874

core/src/test/java/org/elasticsearch/threadpool/ScalingThreadPoolTests.java

@@ -54,7 +54,7 @@ public class ScalingThreadPoolTests extends ESThreadPoolTestCase {
             maxBasedOnNumberOfProcessors = expectedSize(threadPoolName, processors);
             builder.put("processors", processors);
         } else {
-            maxBasedOnNumberOfProcessors = expectedSize(threadPoolName, Math.min(32, Runtime.getRuntime().availableProcessors()));
+            maxBasedOnNumberOfProcessors = expectedSize(threadPoolName, Runtime.getRuntime().availableProcessors());
         }
 
         final int expectedMax;