Shared cache distribution with a single participant

There are cases where a shared cache configured with a max of 20GB, and a single participant. The single participant ends up being allocated only 20MB of the available space.

Review the shared cache algorithm to ensure that a reasonable amount of space is allocated.

The conflict here is that it's (relatively) slow to reclaim space from the shared cache, so allowing a single member to use the entire shared cache will make it slow for new members to get ramped up.

The particular workload does single threaded inserts across several tables, whilst constantly running checkpoints.