Change the links of the purchase add-ons buttons to CustomerDot

Issue link:

• https://gitlab.com/gitlab-jh/gitlab/-/issues/442
• https://gitlab.com/gitlab-jh/gitlab/-/issues/388

What does this MR do

Part One

It's a supplement to the issue: Cancel overriden url of Upgrade button, issue link: https://gitlab.com/gitlab-jh/gitlab/-/issues/388 .

Part two

For update the link of Buy additional minutes button and Purchase more storage button,

override methods in NamespacesHelper: buy_additional_minutes_path and subscriptions_more_storage_url.

Group usage quotas

Personal profile usage quotas