User is searched by the field "user name" with the value for "user key"

In some cases, Xray will use the UserName to fetch the user by UserKey. When the user is created, the user key and user name will have the same value.

If the username is edited it will no longer match the user key and when Xray fetches the user, it will not be able to find it.

One instance where this bug is triggered is when creating a new Test Execution within a Test and assigning a user whose username has been edited.