Re-introduce assertion that issue type is present

What does this MR do?

!41702 (merged) added an attribute to the initial issue data sent to the FE when rendering issues. Looks like the spec accidentally dropped a key from the expected output. This MR puts it back in.

Screenshots

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