Fix flaky Jira issue import spec

What does this MR do?

Fixes a flaky spec by waiting for a flash message that causes the page to shift down.

Closes #227354 (closed)

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