Resolve "Show a meaningful error message when /due quick_actions command fails because the date format is invalid"

What does this MR do?

When an invalid format is given to /due quick actions command a meaningful error message is shown: Failed to set due date because the date format is invalid.

EE port: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/16120

Screenshots

Before	After

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry for user-facing changes, or community contribution. Check the link for other scenarios.
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance 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

Related to #64009 (moved)