WIP: Implement showing CI bridge error messages

WARNING

This is just an approach. Also I wrote some # TODO: comments in code changes to emphasize some wrong approaches.

The proposal in the issue is not suitable for cases when no downstream pipeline created. So in this MR, I suggest to store failure reason, instead of reading from downstream pipeline.

What does this MR do?

Related to: #200016 (closed)

When a bridge job fails to create downstream pipeline, we only show if it is failed or not.

With this, we will start showing error messages.

Screenshots

Example of similar error case stated in #204378 (closed)

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