Fix Counter#decrement recursive call (#5665)

Spigot-API-Patches/Timings-v2.patch

@@ -2041,7 +2041,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +        return increment(key, 1);
 +    }
 +    public long decrement(@Nullable T key, long amount) {
-+        return decrement(key, -amount);
++        return increment(key, -amount);
 +    }
 +    public long increment(@Nullable T key, long amount) {
 +        Long count = this.getCount(key);