Manual job execution - provided variables not cleared on retry

Related to implementation issue: Frontend: Surface the used custom variables for manual jobs and allow to retry the job with updated variables

We have an issue that can be reproduced as follows

• Create a pipeline with a manual job
• Run the pipeline and wait until it gets to the manual job where user interaction is required
• Add a variable on the trigger job screen and populate its value
• Click run job to execute
• Go back to the job and from the drop down select "Update CI/CD Variables"
• This brings you back to the "Run Job" screen, where the previously entered variable is visible in plaintext.
• We would like all fields to be blank instead of the previously entered value being visible

I understand that this functionality could be useful in certain scenarios, but in our use case, we do not want to give somebody the possibility to copy the job input parameters after the job has run. Ideally, a flag could be set to enable/disable variable masking.