Implement post-release one login banner for sign in page

[elceebee]

Context

We are currently displaying a service banner letting people know that one login is coming on the sign in page. Once it is live, we want to show a different banner.

Changes proposed in this pull request

Pre-release	Post-release

Guidance to review

Can be viewed locally or on the review app at /rails/view_components/candidate_interface/one_login_pre_release_banners/one_login_post_release_sign_in_banner_component, or if the one login feature is turned on, at /candidate/account

Link to Trello card

https://trello.com/c/oXhetRk7

Things to check

• If the code removes any existing feature flags, a data migration has also been added to delete the entry from the database
• This code does not rely on migrations in the same Pull Request
• If this code includes a migration adding or changing columns, it also backfills existing records for consistency
• If this code adds a column to the DB, decide whether it needs to be in analytics yml file or analytics blocklist, if included inform data insights team of the changes
• If this code adds a column that may include PII, the sanitise.sql script and 0025-protecting-personal-data-in-production-dump.md ADR have been updated.
• API release notes have been updated if necessary
• If it adds a significant user-facing change, is it documented in the CHANGELOG?
• Attach the PR to the Trello card

[elceebee]

One Login: Update sign-in service banner's content upon Release