This is a follow up to ed11ee9d05.
In `Chat::AutoRemove::HandleCategoryUpdated`, we are currently loading
the related users record in batches and then handing it off to
`Chat::Action::CalculateMembershipsForRemoval.call`. However, we are
still seeing memory spike as a result of this.
This commit eliminates the allocation of `User` ActiveRecord objects until
absolutely necessary. `Chat::Action::CalculateMembershipsForRemoval.call` has been
updated to accept an ActiveRecord relation instead which allows us to
avoid the ActiveRecord allocations.