Splitting this ticket from SERVER-92333 for each team. Copying the description over:

Scheduling tasks on a cancellation token will keep those tasks alive in-memory until the token's underlying CancellationSource is destructed. If a cancellation source stays alive for a long time and has many tasks scheduled on it, this can lead to significant memory use, as in SERVER-92236. We should audit our use of cancellation sources for any that can live for a long time and probably rewrite them to at least periodically be cleared.