fix: don't support cgroups nesting in process runner

This was left from my attempts to fix the tests.

When Talos runs as OS, it should never try to nest cgroups, as machined
itself runs as `/system/init` and it shouldn't nest inside that cgroup.

Signed-off-by: Andrey Smirnov <andrey.smirnov@talos-systems.com>

internal/app/machined/pkg/system/runner/process/process.go

@@ -107,7 +107,7 @@ func (p *processRunner) build() (cmd *exec.Cmd, logCloser io.Closer, err error)
 	return cmd, w, nil
 }
 
-//nolint:gocyclo,cyclop
+//nolint:gocyclo
 func (p *processRunner) run(eventSink events.Recorder) error {
 	cmd, logCloser, err := p.build()
 	if err != nil {
@@ -132,19 +132,12 @@ func (p *processRunner) run(eventSink events.Recorder) error {
 	// it's not easy to fail (as the process has to be cleaned up)
 	if p.opts.CgroupPath != "" {
 		if cgroups.Mode() == cgroups.Unified {
-			var groupPath string
-
-			groupPath, err = cgroupsv2.NestedGroupPath(p.opts.CgroupPath)
-			if err != nil {
-				return fmt.Errorf("failed to compute group path: %w", err)
-			}
-
-			cgv2, err = cgroupsv2.LoadManager(p.opts.CgroupPath, groupPath)
+			cgv2, err = cgroupsv2.LoadManager(constants.CgroupMountPath, p.opts.CgroupPath)
 			if err != nil {
 				return fmt.Errorf("failed to load cgroup %s: %w", p.opts.CgroupPath, err)
 			}
 		} else {
-			cgv1, err = cgroups.Load(cgroups.V1, cgroups.NestedPath(p.opts.CgroupPath))
+			cgv1, err = cgroups.Load(cgroups.V1, cgroups.StaticPath(p.opts.CgroupPath))
 			if err != nil {
 				return fmt.Errorf("failed to load cgroup %s: %w", p.opts.CgroupPath, err)
 			}