Fix design comment pin sizing bug

What does this MR do?

Sometime recently, a regression was introduced where pins for new design comments were both:

• too small
• slightly incorrectly positioned

This MR:

• Fixes both issues
• Uses GlIcon in the component

Note: the Design Management application is moving, and this move is currently in progress (hence, changes to both design_management and design_management_new). This MR fixes the issue in both versions of the component.

Screenshots

Notice in "Before" demo that the pin:

• is too small compared to the hover state
• doesn't fall directly under the mouse click (is placed slightly below and to the right)

Before	After
design-pin-broken	dsign-ping-fixed

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