Limit subscription page container to 990px

What does this MR do and why?

It limits the width of the subscription page to 990px. It also unifies the spacing between subscription details card buttons.

Screenshots or screen recordings

before	after

How to set up and validate locally

1. with root user navigate to admin > subscription page

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.

Related to #337026