Reviewers of a merge request should not be subscribed to the MR.
Description
Currently, when a user is added as a potential reviewer of a merge request, that uer is automatically subscribed to the merge request and will begin reeiving notifications for comments and pipeline failures. This can be troublesome for some workflows.
for example on my project we add the entire team (~10 people) as potential reviewers, and one or two people will chose to pick up the MR to review it. But all other people are subscribed to the MR even though they may have no interest in it.
This is also a surprising feature, because this means a user can be subscribed to the MR by someone else, which is surprising in this case.
Proposal
Make it so the reviewers assigned to a MR at the MR creation time are not subscribed by default. I would be fine with an option to re-enable this behaviout but it is not essential in my opinion.