cgroup2: Revert "CreateCgroupPath: only enable needed controllers"

[AkihiroSuda]

CreateCgroupPath: only enable needed controllers (4b4bc99) seems problematic toward supporting nested containers. (#2356)

As many controller s as possible should be always enabled.

cc @kolyshkin

[AkihiroSuda]

@kolyshkin WDYT?

[kolyshkin]

Enabling a controller should negatively affect performance (since some accounting for the resource(s) controlled are to be done by the kernel) -- even in the case no limits are set.

So, this is a trade-off between best performance and versatility. Ideally, I'd like it to be configurable (i.e. there should be a way to just enable a controller but do not set any limits, which is currently impossible).

Until we have this ability, either way is fine with me (all controllers or on-demand). Since we used to have all controllers, let's do that.

[AkihiroSuda]

resolved in #2395