Copy adjustment for /billings page Duo Pro hand-raise PQL

What does this MR do and why?

Resolves https://gitlab.com/gitlab-org/gitlab/-/issues/438819

Copy adjustment for /billings page Duo Pro hand-raise PQL

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Setup GDK to simulate SaaS
2. Enable FF with echo "Feature.enable :cs_connect_with_sales" | gdk rails c
3. Visit http://gdk.test:3000/groups/<group_name>/-/billings for a namespace not on a trial (you may need Customer Dot running)
4. See Due Pro card

Related to #438819