Fix Sonar code smell issue

Sonar does not allow constant definitions in interfaces. Remove the
REVERSE_ORDER_COMPARATOR constant, which was used only in a single
method within this interface.

Change-Id: If1569c0c0dea61a330f1d7c03e0171980e3d4b87
diff --git a/src/main/java/com/googlesource/gerrit/plugins/ratelimiter/RateLimiter.java b/src/main/java/com/googlesource/gerrit/plugins/ratelimiter/RateLimiter.java
index 81280ba..7c695de 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/ratelimiter/RateLimiter.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/ratelimiter/RateLimiter.java
@@ -18,12 +18,10 @@
 import java.util.concurrent.TimeUnit;
 
 interface RateLimiter extends Comparable<RateLimiter> {
-  Comparator<RateLimiter> REVERSE_ORDER_COMPARATOR =
-      Comparator.comparing(RateLimiter::availablePermits).reversed();
 
   @Override
   public default int compareTo(RateLimiter other) {
-    return REVERSE_ORDER_COMPARATOR.compare(this, other);
+    return Comparator.comparing(RateLimiter::availablePermits).reversed().compare(this, other);
   }
 
   /** Returns number of permits allowed per hour. */