sweet/benchmark/internal/cgroups: test system-run functionality

Add a rudimentary test for starting a user scope with systemd-run. If it
doesn't work, then skip the wrapper.

For golang/go#54760.

Change-Id: I7b742b49ae453b8d485d7d0c008b9fb9148c37ac
Reviewed-on: https://go-review.googlesource.com/c/benchmarks/+/426238
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
1 file changed