cgroups: Fix race to load cgroup.hostRoot option

[kvaps]

While loading, the package pkg/cgroups/manager sets the global variable cgroupRoot from the pkg/cgroups package.
This occurs before the configuration is fully loaded and the correct path is set in the pkg/cgroups package.

This variable is later used by the validateCgroupPath function.
As a result, the validateCgroupPath function always works with the default value instead of the user-defined one.

While using --set cgroup.autoMount.enabled=false and --set cgroup.hostRoot=/sys/fs/cgroup options, this might lead strange errors like:

level=info msg="  --cgroup-root='/sys/fs/cgroup'" subsys=daemon
level=info msg="Mounted cgroupv2 filesystem at /sys/fs/cgroup" subsys=cgroups
level=warning msg="No valid cgroup base path found: socket load-balancing tracing with Hubble will not work.See the kubeproxy-free guide for more details." subsys=cgroup-manager

And path /sys/fs/cgroup/kubepods correctly existing.

cgroups: Fix race to load cgroup.hostRoot option

[aspsk]

Thanks @kvaps, the change looks great! However, it breaks the pkg/cgroups/manager/manager_test.go and the pkg/cgroups/manager/provider_test.go tests, as they use the variable you've removed. Could you please patch the tests as well?

[kvaps]

Yeah, sorry, added it to provider_test.go

[aspsk]

@kvaps thanks. Could you also please rebase on top of main?

[kvaps]

Sure, done

[aspsk]

/test

[aspsk]

Thanks!