Ensure all scanners are translated in alerts

What does this MR do and why?

This adds a translation for SAST_IAC for the security-scanner-alert component to render a user-friendly name. It also slightly changes how scanner names' translations are organized so that it's harder to forget to provide one when adding a new scanner.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. In a project that doesn't have SAST_IAC enabled, navigate to the vulnerability report at /:namespace/:project/-/security/vulnerability_report

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 #347133 (closed)