fix: remove LXC working directory when it completes

The working directory was not cleaned up upon completion of a LXC job because
rc.stopJobContainer() -> rc.cleanUpJobContainer() -> rc.JobContainer.Remove()
was never called for LXC containers.

- stopContainer() and closeContainer() must not call
  rc.stopHostEnvironment(ctx) for LXC containers because
  - it will needlessly be called twice
  - it intercepts the call to
    - rc.stopJobContainer()
    - rc.JobContainer.Close()
- rc.stopHostEnvironment(ctx) must be called in rc.cleanUpJobContainer
  which is indirectly called by rc.stopJobContainer()
- since rc.JobContainer.Close() is a noop, not calling it for LXC
  containers had no consequence

Resolves forgejo/runner#442

act/container/host_environment.go

@@ -407,6 +407,7 @@ func (e *HostEnvironment) Remove() common.Executor {
 		if e.CleanUp != nil {
 			e.CleanUp()
 		}
+		common.Logger(ctx).Debugf("HostEnvironment.Remove %s", e.Path)
 		return os.RemoveAll(e.Path)
 	}
 }