Fix dast-site-profiles query

What does this MR do?

It fixes a graphql-query that selects DAST on-demand scanner profiles, which includes a wrong field selector (DASTSiteProfiles instead of dastSiteProfiles).

The feature is currently behind an auto-disabled feature flag, so no changelog is needed.

More context can be found in this discussion.

before 🙀	after 🥳

Proof 🚓

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Related to #229516 (closed)