Fix docs to list dependency proxy as premium

Some areas of the docs incorrectly listed the
dependency proxy as an ultimate feature.

doc/administration/high_availability/object_storage.md

@@ -22,7 +22,7 @@ For configuring GitLab to use Object Storage refer to the following guides:
 1. Configure [object storage for container registry](../packages/container_registry.md#container-registry-storage-driver) (optional feature).
 1. Configure [object storage for Mattermost](https://docs.mattermost.com/administration/config-settings.html#file-storage) (optional feature).
 1. Configure [object storage for packages](../packages/index.md#using-object-storage) (optional feature). **(PREMIUM ONLY)**
-1. Configure [object storage for dependency proxy](../packages/dependency_proxy.md#using-object-storage) (optional feature). **(ULTIMATE ONLY)**
+1. Configure [object storage for dependency proxy](../packages/dependency_proxy.md#using-object-storage) (optional feature). **(PREMIUM ONLY)**
 1. Configure [object storage for Pseudonymizer](../pseudonymizer.md#configuration) (optional feature). **(ULTIMATE ONLY)**
 
 NOTE: **Note:**

doc/administration/packages/dependency_proxy.md

-# GitLab Dependency Proxy administration **(ULTIMATE ONLY)**
+# GitLab Dependency Proxy administration **(PREMIUM ONLY)**
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/7934) in [GitLab Premium](https://about.gitlab.com/pricing/) 11.11.
 

doc/user/packages/dependency_proxy/index.md

-# Dependency Proxy **(ULTIMATE ONLY)**
+# Dependency Proxy **(PREMIUM ONLY)**
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/7934) in [GitLab Ultimate](https://about.gitlab.com/pricing/) 11.11.