Improve generated integration tests

- Save logs from control(headscale) on every run to tmp
- Upgrade nix-actions
- Cancel builds if new commit is pushed
- Fix a sorting bug in user command test

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

integration/control.go

@@ -6,6 +6,7 @@ import (
 
 type ControlServer interface {
 	Shutdown() error
+	SaveLog(string) error
 	Execute(command []string) (string, error)
 	GetHealthEndpoint() string
 	GetEndpoint() string