Align secrets manager banner states to design specs pt.1

What does this MR do and why?

This is the first MR out of a series of MRs to update the various banner states for the secrets manager to match the design specs. This was primarily made up of two parts, updating content in the banners and extracting some of the banners into reusable components since the next MR will involve mirroring the banner states onto the secrets manager settings area for root groups on SaaS.

Main changes:

• Updated the copy and content of the trial state banners
• Previously when the beta banners rendered without showing the CTAs it rendered "Contact your administrator to start a trial." as a replacement, thats been removed now as per the designs
• Extracted the paid state banner that indicates credit consumption previously only showing up in the Admin area, into a reusable component for the next stage of work. Same with the trial state banners.
• Updated the trial banner to no longer appear when all trial credits have been used up and on-demand is enabled

Next steps:

• MR2 will add the relevant banner states to the secrets manager settings area for SaaS
• Updating the subscription grace period banner which will happen after !257032 (merged)
• Updating the enable_add_on banner CTA to be gated by !256662 (merged)

References

Figma link First stage of #629113 (closed)

Screenshots or screen recordings

State	Before	After
Trial, high credits	no banner
Trial, under 10% credits
Blocked (e.g. on-demand disabled), trial expired
Blocked (e.g. on-demand disabled), credits exhausted

How to set up and validate locally

1. Make sure you're running on SaaS: GITLAB_SIMULATE_SAAS=1 gdk start
2. Set up the GDK with OpenBao: https://gitlab.com/gitlab-org/gitlab-development-kit/-/blob/main/doc/howto/openbao.md
3. Enable the following feature flags: secrets_manager, group_secrets_manager, secrets_manager_namespace_enrollment, secrets_manager_paid_experience.
4. Stub the CustomersDot entitlement as trial_eligible with on-demand billing, for example with the dev-only resolver stub from !253618 (merged). I'd recommend asking claude to swap between the various states as an effective method
5. Verify some of the main claims such as the trial banner appearing when in the trial state showing the % of credits left and the days left

MR acceptance checklist

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