Resolve "Iteration not added to issue in iterations board list"

What does this MR do and why?

Describe in detail what your merge request does and why.

Adding possibility to assign the iteration to the new issue when created on a board list.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Screenshots

before	after

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Visit project or group page
2. Visit Issues > Iterations
3. Create new iteration (if not exist)
4. Visit Issues > Boards
5. Add an iterations list to a board.
6. Add a new issue using + button.
7. Check that the created issue have the iteration assigned.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #372322 (closed)