Smart redirect to onboarding project after import

What does this MR do?

The "trial onboarding" experiment creates a "GitLab onboarding" project, which is imported in the background.

We redirect to the particular board if available (if project is imported), whenever the user clicks the action link.

In contrast to GDK, On gitlab.com each project has a default second board seeded earlier, in addition to the "GitLab onboarding" board we create. So we end up not seeing our board but the list of boards.

Followup for !48052 (merged)

gitlabhq_production=> select count(*) from boards where name = 'GitLab onboarding';
 count  
--------
 118913

Screenshots

Before boards screen	After the board

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