Draft: Make the Orbit texts true for each state [skip ci]

What does this MR do and why?

Code fixes from the Orbit copy review, so that the text is correct for the state where it shows. Stacked on !263732 (merged).

• Query editor: an administrator on GitLab Self-Managed gets an admin text (start the trial, with a link to the GitLab Orbit settings, or contact sales) and no longer "Ask your administrator".
• Admin card: when the trial credits are used up before the end date, the card says "Credits used up" and shows no end date.
• Error message: "Only top-level groups can be indexed." goes on :base, so users no longer see "Root namespace Only top-level groups …".
• Group settings: a queued group polls every 60 seconds, so "A message appears here when GitLab Orbit is ready" is true.
• Small changes: no "Additional metadata if required" placeholder on the health card, no "Not available" badge on the admin card, a clearer fallback trial error, and the global "Cancel".

Screenshots or screen recordings

Self-Managed, as the administrator. Before: the base of this MR (64bfbd5d, !263732 (merged)). After: 40968abd. The admin card states that the local CustomersDot cannot make are rewritten in the browser; the page code is real.

Item	Before	After
A1: Query editor, administrator, the instance can start a trial
A1: Query editor, administrator, the instance needs a purchase
A2: Admin card, the trial credits are used up before the end date (access answer rewritten in the browser)
C2: Admin health card, components with metadata (status answer rewritten in the browser)
C3: Admin card, no license for GitLab Orbit (access answer rewritten in the browser)

Videos:

A1, the instance can start a trial: before

A1, the instance can start a trial: after

A1, the instance needs a purchase: before

A1, the instance needs a purchase: after

No visible change: A3 and C5 are messages that the UI almost never shows, A4 is a polling interval, and C6 is the same "Cancel" text. The specs cover them.

How to set up and validate locally

All Orbit Jest specs pass (1359). The changed RSpec files pass.