Improve reusability in On-demand DAST Scans form

• Related issue: #246780 (closed)

What does this MR do?

In !41922 (merged), we have created profile selector components that abstract the profile selectors in the On-demand scans form. This MR is the second and last step of this code refactor which involves actually using those new components, which lets us drop a bunch of duplicated code.

This also cleans up related specs by removing some computed props tests in favor of implicit UI tests and other minor improvements.

Screenshots

The only visible change is the cards' titles that have been updated to align with the latests designs.

Before	After

Does this MR meet the acceptance criteria?

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
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done