Add content for retried manual builds

What does this MR do and why?

Above the form to enter variables, manual jobs have the text:

This job requires manual intervention to start. Before starting this job, you can add variables below for last-minute configuration changes.

Now that manual jobs can be retried with new variables, we need new text that is more accurate for a retryable job:

This job can be run again. Before running this job again, you can modify its variables below.

This MR adds that text.

Screenshots or screen recordings

Before:

After:

How to set up and validate locally

1. Create a pipeline with a manual job (it does not matter if that job will succeed or fail)
2. Before playing the manual job, notice the text This job requires manual intervention to start. Before starting this job, you can add variables below for last-minute configuration changes. on the manual job show page
3. Play the manual job
4. On the manual job show page, navigate to the option to retry the manual job in the top right
5. Select Update CI/CD variables
6. Above the variables form, notice the text This job can be run again. Before running this job again, you can modify its variables below.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

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

Related to #381803 (closed)