Fix displaying merge request dependencies with no metrics

What does this MR do?

Metrics may not exist for some older MRs, so we need to &.latest_closed_at

Screenshots (strongly suggested)

Here's how we look with a non-metrics blocking MR now:

Perfectly fine :)

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 /ee/development/contributing/merge_request_workflow.html#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 #209853 (closed)