job_manager/create: add cache_size limit

5 jobs from resource-control in 1 minute and 16 seconds (queued for 7 seconds)
latest
Status Job ID Name Coverage
  Test
passed #184798
docker linux amd64
test:flake8

00:00:21

passed #184797
docker linux amd64
test:mypy

00:00:24

passed #184799
docker linux amd64
test:pylint

00:00:36

passed #184800
docker linux amd64
test:pytest

00:00:20

passed #184801
docker linux amd64
test:respdiff

00:01:15