test/cgroups.bats: simplify and fix
test/cgroups.bats: simplify and fix

1. If possible, do not use `run`. For example, the following code

```bash
run crictl create ...
echo "$output"
[ "$status" -eq 0 ]
ctr_id="$output"
```

is equivalent to

```bash
ctr_id=$(crictl create ...)
```

and the latter is much more comprehensible.

2. Remove explicit test cleanup (pods and containers removal), as
   cleanup_test is doing it anyway.

3. Replace `crictl pod; crictl create; crictl start` with `crictl run`
   for brevity.

4. When making custom configs, avoid using cat and temporary variables.

Signed-off-by: Kir Kolyshkin <3a017b8ddb3f9cf3e4a59978b004111bdeb97f08@gmail.com>

kubernetes-incubator/cri-o,kubernetes-incubator/cri-o,kubernetes-incubator/cri-o,kubernetes-incubator/ocid,kubernetes-incubator/ocid,nalind/cri-o,nalind/cri-o,kubernetes-incubator/cri-o,nalind/cri-o,kubernetes-incubator/ocid