Revert "Make scheduler threads share memory more quickly"
Revert "Make scheduler threads share memory more quickly"

This reverts commit 5494d9b3ea54d33617894bd7e3b0c4b6b10e7078.

The above commit was intended to leave a smaller memory footprint
that stabilized at a quicker rate. However, testing using Wallaroo's
Market Spread application showed explosive memory growth when dealing
with a high workload. After speaking to @dipinhora about the issue, he
suggested reverting the commit as this was not the effect intended
by his change. He suspects the issue might be due to how the
`pool_pull` function behaves but has not had the time to investigate
to confirm. For additional information on the suspected cause of the
bug, contact @dipinhora.

CausalityLtd/ponyc,CausalityLtd/ponyc,kulibali/ponyc,Theodus/ponyc,kulibali/ponyc,jemc/ponyc,cquinn/ponyc,cquinn/ponyc,CausalityLtd/ponyc,sgebbie/ponyc,dipinhora/ponyc,Theodus/ponyc,jemc/ponyc,sgebbie/ponyc,ponylang/ponyc,Theodus/ponyc,Theodus/ponyc,jemc/ponyc,cquinn/ponyc,ponylang/ponyc,ponylang/ponyc,sgebbie/ponyc,dipinhora/ponyc,Theodus/ponyc,kulibali/ponyc,cquinn/ponyc,sgebbie/ponyc,kulibali/ponyc,sgebbie/ponyc,dipinhora/ponyc