Use crosshair cursor when hovering on the design view

What does this MR do?

Use cursor: crosshair; for cursor when hovering over a design.

Various simplifications/removals have also been made to the template and specs, mostly accessibility-related and to use gitlab-ui utilities where possible.

Original issue: #225242 (closed)

Screenshots

Before	After
no_crosshair	crosshair

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

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team