Upgrade DAST templates to default to version 5

What does this MR do and why?

Upgrades the default version of DAST to be version 5, not version 4. This is a breaking change that is intended to be released during the third breaking changes window, sometime between 2024-05-06 09:00 UTC to 2024-05-08 22:00 UTC.

MR acceptance checklist

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Screenshots or screen recordings

Screenshot of job using new template