Plan::ULTIMATE_TRIAL_PAID_CUSTOMER include guest as billable

What does this MR do and why?

Solve issue Plan::ULTIMATE_TRIAL_PAID_CUSTOMER include gues... (#432525 - closed)

We expect ultimate_trial_paid_customer plan follow the same rule as premium plan when calculate seat usage. It should count guest users as billable users.

To achieve this goal, this MR removes Plan::ULTIMATE_TRIAL_PAID_CUSTOMER from the exclude_guests? plan list.

Screenshots or screen recordings

Find a group and set the GitlabSubscription plan to Plan::ULTIMATE_TRIAL_PAID_CUSTOMER.

Add a guest user to the group, the guest user is using seats

How to set up and validate locally

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.