SERVER-73128 added the possibility of globally enabling/disabling the auto-merger. Purpose of this ticket is to add a new parameter to configureCollectionBalancing in order to also allow enabling/disabling it on a per-collection basis.

(Only possible starting from v7.1 due to SERVER-73580) EDIT: after further evaluation there is no risk doing this in pre-v7.1 versions. The worst that could happen is that parsing fails for a command sent to an old binary with the new parameter. And that's fine.