Removed fetching unused properties for subscription

What does this MR do and why?

Cleans up unused properties for subscription flow

With the bug fix for #352231 merged !82480 (merged), we no longer need guests and users for new subscription flow.

present_group is also used to fetch addon data, but it looks like users property wasn't actually being used in addon purchase flow. So I've removed both users and guests from being fetched.

Screenshots or screen recordings

Addon and subscription purchase flows behave as it used to

Minutes before purchase	Purchase screen	Minutes after purchase

Storage before purchase	Purchase screen	Storage after purchase

Subscription purchase

How to set up and validate locally

1. Make sure self.com? return true in gitlab.rb
2. Visit Usage quotas page for a group which has a project ex. http://localhost:3000/groups/test/-/usage_quotas?
   • Go to Pipelines tab and buy more minutes
   • Go to Storage tab and buy more storage

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.