Convert stylesheets/pages/error_list.scss into page specific bundle

What does this MR do?

Moves error_list.scss to a page specific bundle and includes it on the relevant page. Also combines error_tracking_list.scss into the new page bundle.

How to test

You can run the branch locally and the on-screen output should be exactly the same, except the page-specific styles will come from a different file, not application.css.

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

Related to #239827 (closed)