Assignee change email notification is difficult to read with multiple names

Problem to solve

The email notifications for assignee changes get very long and not easy to read when several people are assigned to an issue. Internally, this happens often while an issue is being reviewed by frontend , backend, and database at the same time.

Screenshots

Proposal

Change the wording to match the implementation for reviewers (Issue 357302 reviewer changed email notification (!98889 - merged))

Example:

List of 5 assignees, one is removed:

@user1 was removed as assignee

Instead of:

Assignees changed from @user1, @user2, @user3, @user4, @user5 to @user2, @user3, @user4, @user5