By default disable auto update of addons

What does this MR do?

When ZAP runs it automatically attempts to update all of it's addons to the latest version. This can break DAST.

This MR updates the DAST config to disable addon auto-update by default.

This change is documented in 30677

What are the relevant issue numbers?

#198456

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated for GitLab EE, if necessary
• Documentation created/updated for this project, if necessary
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Job definition updated, if necessary
  • Job definition example
  • Vendored CI Templates (also in CE)
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer