security: use correct time unit for role cache expire after write

The role cache was previously using the wrong time unit for its expire after write time; the
value passed to the cache was milliseconds instead of nanoseconds.

Original commit: elastic/x-pack-elasticsearch@65f7b08763

elasticsearch/src/main/java/org/elasticsearch/xpack/security/authz/store/NativeRolesStore.java

@@ -135,7 +135,7 @@ public class NativeRolesStore extends AbstractComponent implements RolesStore, C
         this.client = client;
         this.roleCache = CacheBuilder.<String, RoleAndVersion>builder()
                 .setMaximumWeight(CACHE_SIZE_SETTING.get(settings))
-                .setExpireAfterWrite(CACHE_TTL_SETTING.get(settings).getMillis())
+                .setExpireAfterWrite(CACHE_TTL_SETTING.get(settings).getNanos())
                 .build();
         this.isTribeNode = settings.getGroups("tribe", true).isEmpty() == false;
     }