Preserve Epics state on Group Import

What does this MR do?

This MR fixes a bug with Epics not preserving their state on Group Import. No matter the state (opened/closed) - imported epics would always be imported as 'opened'. This is because our AttributeCleaner was cleaning up state_id. And our unit tests did not catch this problem because every epic in the fixture files had opened state. And looks like we were not testing that state has been Imported properly.

Screenshots

Before:

After:

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