Expand scaling thread pool configuration coverage

This commit slightly expands the scaling thread pool configuration test
coverage. In particular, the test testScalingThreadPoolConfiguration is
expanded to include the case when min is equal to size, and the test
testDynamicThreadPoolSize is expanded to include all possible cases when
size is greater than or equal to min.

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

@@ -59,7 +59,7 @@ public class ScalingThreadPoolTests extends ESThreadPoolTestCase {
 
         final int expectedSize;
         if (sizeBasedOnNumberOfProcessors < min || randomBoolean()) {
-            expectedSize = randomIntBetween(min + 1, 16);
+            expectedSize = randomIntBetween(min, 16);
             builder.put("threadpool." + threadPoolName + ".size", expectedSize);
         }  else {
             expectedSize = sizeBasedOnNumberOfProcessors;
@@ -188,12 +188,12 @@ public class ScalingThreadPoolTests extends ESThreadPoolTestCase {
         final String threadPoolName = randomThreadPool(ThreadPool.ThreadPoolType.SCALING);
         runScalingThreadPoolTest(Settings.EMPTY, (clusterSettings, threadPool) -> {
             final Executor beforeExecutor = threadPool.executor(threadPoolName);
-            final int size = randomIntBetween(128, 512);
+            int expectedMin = "generic".equals(threadPoolName) ? 4 : 1;
+            final int size = randomIntBetween(expectedMin, Integer.MAX_VALUE);
             clusterSettings.applySettings(settings("threadpool." + threadPoolName + ".size", size));
             final Executor afterExecutor = threadPool.executor(threadPoolName);
             assertSame(beforeExecutor, afterExecutor);
             final ThreadPool.Info info = info(threadPool, threadPoolName);
-            int expectedMin = "generic".equals(threadPoolName) ? 4 : 1;
             assertThat(info.getMin(), equalTo(expectedMin));
             assertThat(info.getMax(), equalTo(size));