Email notification for Assignee change became messy

Earlier, the email notification for Assignee changed contained the following

Assignee changed from John Doe to Jane Doe

Recently, it changed to

Reassigned Merge Request NNNN https://gitlab.com/XYZ/MNO/merge_requests/NNNN Assignee changed from John Doe to Jane Doe

Things I find messy

1. Missing period between two statements
2. Open link
3. Redundant information - Reassigned and Assignee changed. This may be better Reassigned [Merge Reqest NNNN](https://gitlab.com/XYZ/MNO/merge_requests/NNNN) from John Doe to Jane Doe

/cc @marin