Not use the word retry to refer to webhook executions

What does this MR do and why?

Prior to this change, we were confusing users and giving them the impression that webhook events would be resent if they failed. We do not do that.

This change avoids the use of retry.

How to set up and validate locally

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

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.