Migrate fa-spinner to spinner in views dashboard.

What does this MR do?

Migrates the use of .fa-spinner icons to .spinner ones where previously = spinner was used in app/views/dashboard/. See #202580 (closed)

This does NOT change the previous use of icon('spinner spin') in app/views/dashboard/todos as that will be handled by a separate ticket #202601 (closed)

NOTE: I was not able to test this on IE11 and Edge as I am on Mac and the current tools I have for testing are not working with my local setup.

Screenshots

Chrome

Safari

Firefox

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