Update copy for pipeline execution type policy selector

What does this MR do and why?

This MR updates copy for pipeline execution type

New pipeline execution policy type has new card for type selector

Copy is adjusted according to design

MR acceptance checklist

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

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

UI

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Enable feature flag

   Feature.enable(:pipeline_execution_policy_type)

2. Go to Settings -> General

3. Toggle the Permissions and group features section

4. Enable Security policy pipeline execution action

5. Go to project/group

6. Secure -> Policies

7. New policy, you should see 3 cards with updated copy

Related to #454843 (closed)