Fix DefaultEnvTest.incBackgroundThreadsIfNeeded test (#5021)

Summary:
`DefaultEnvTest.incBackgroundThreadsIfNeeded` jtest should assert that the number of threads is greater than or equal to the minimum number of threads.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5021

Differential Revision: D14268311

Pulled By: sagar0

fbshipit-source-id: 01fb32b5b3ce636451d162fa1a2bbc5bd1974682

java/src/test/java/org/rocksdb/DefaultEnvTest.java

@@ -54,13 +54,13 @@ public class DefaultEnvTest {
   public void incBackgroundThreadsIfNeeded() {
     try (final Env defaultEnv = RocksEnv.getDefault()) {
       defaultEnv.incBackgroundThreadsIfNeeded(20, Priority.BOTTOM);
-      assertThat(defaultEnv.getBackgroundThreads(Priority.BOTTOM)).isEqualTo(20);
+      assertThat(defaultEnv.getBackgroundThreads(Priority.BOTTOM)).isGreaterThanOrEqualTo(20);
 
       defaultEnv.incBackgroundThreadsIfNeeded(20, Priority.LOW);
-      assertThat(defaultEnv.getBackgroundThreads(Priority.LOW)).isEqualTo(20);
+      assertThat(defaultEnv.getBackgroundThreads(Priority.LOW)).isGreaterThanOrEqualTo(20);
 
       defaultEnv.incBackgroundThreadsIfNeeded(20, Priority.HIGH);
-      assertThat(defaultEnv.getBackgroundThreads(Priority.HIGH)).isEqualTo(20);
+      assertThat(defaultEnv.getBackgroundThreads(Priority.HIGH)).isGreaterThanOrEqualTo(20);
     }
   }