What does this MR do and why?

Update Premium billing page to adapt trial flow changes

References

Screenshots or screen recordings

Before	After

How to set up and validate locally

• Setup gdk to simulate SaaS - https://docs.gitlab.com/ee/development/ee_features.html#simulate-a-saas-instance and restart GDK
• Sign in as root. Create new group.
• In admin section update plan to be premium.
• Visit /-/billings page.

MR acceptance checklist

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

Related to #587958

LGTM! @jivanvl can you do the maintainer review?

suggestion (non-blocking): I remember seeing warnings in the Danger bot about not using classes like gl-bg-blue-50 (maybe only when in vue files). Instead, we should use the semantic equivalent. I found that gl-bg-feedback-info maps to gl-bg-blue-50 in light mode: https://design.gitlab.com/tailwind-documentation/background-color. But the context of this banner does not really fit the "feedback-info" wording, so I am not sure.

@cngo thanks for reviewing! Yes, there's quite a bit of unreachable code that can be deleted; I'll address that in separate MRs.

Yeah, the old billing app and components are quite large, so I plan to remove them entirely in a separate MR.

@vvempati can you do the initial frontend review?

@pgascouvaillancourt can you do the initial backend and test review?

Roy Liu (de9b1366) at 16 Mar 19:53

Roy Liu (7855b05c) at 16 Mar 19:17

Relates to https://gitlab.com/gitlab-org/gitlab/-/work_items/593618

Summary

This MR removes the enable_free_purchase_dap_monthly_commit feature flag, it has been rolled out to 100% in production since March 12th: https://gitlab.com/gitlab-com/gl-infra/feature-flag-log/-/work_items/55737.

Permanently enabling the new group billing's page for free and trial namespaces. It also productizes some UX updates for Trial CTAs on GitLab Credits Page, GitLab Duo Page and End of Trial Modal.

• Initial implementation for new billings page: https://gitlab.com/gitlab-org/gitlab/-/work_items/591000
• UX updates for trial CTAs: https://gitlab.com/gitlab-org/gitlab/-/work_items/591001

Unreachable code (mostly frontend) will be cleanup in follow-up MRs to keep this MR small for review.

@dstull Addressed the latest comments 🏓

Roy Liu (985c1e62) at 16 Mar 17:51

Good point, adding the failure path.

We shouldn't need to, at the point of rendering resubmit component, these three fields are already stored in onboarding_status, CreateLeadService just reads them from database.

Thanks for catching this.

@mbenayoun thanks for reviewing, can you help set merge?