Reword, move variable modal AWS/OIDC guidance

What does this MR do and why?

For #391817 (closed)

Reword, move variable modal AWS/OIDC guidance

When modal shows a variable that's one of the AWS_TOKEN_CONSTANTS, an alert should be shown with guidance on how to configure OIDC to get these credentials instead of using variables. This MR moves the alert to the top of the modal and updates its message to be more generic with a link to the OIDC documentation.

Changelog: changed

Screenshots or screen recordings

Before	After
Screen_Recording_2023-08-03_at_23.50.32	Screen_Recording_2023-08-03_at_17.30.40

How to set up and validate locally

git checkout 391817-move-aws-oidc-banner

1. this is a shared component, it should work the same way in these three places:
   • instance variables: navigate to the Admin Area, then in the sidebar choose Settings => CI/CD (http://gdk.test:3000/admin/application_settings/ci_cd), then expand the Variables section
   • group variables: navigate to a group, then in the sidebar choose Settings => CI/CD (http://gdk.test:3000/groups/flightjs/-/settings/ci_cd), then expand the Variables section
   • project variables: navigate to a project, then in the sidebar choose Settings => CI/CD (http://gdk.test:3000/flightjs/Flight/-/settings/ci_cd), then expand the Variables section
2. add a new variable and name it AWS_ACCESS_KEY_ID, AWS_DEFAULT_REGION, or AWS_SECRET_ACCESS_KEY
   • an alert should appear at the top of the variable modal prompting you to set up OIDC to retrieve these values
   • if you save the variable and open it again to edit it, the alert should still be there
3. add a new variable and name it anything else
   • the alert should not be shown
4. edit the AWS_* variable and dismiss the alert
   • a ci_variable_list_constants_aws_tip_dismissed cookie should be set and stored for 90 days
   • while this cookie is present the alert will not be shown again (even for a different group/project or for a different variable name)

to run tests

yarn install
yarn jest ci_variable_list/components

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.