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>

.github/workflows/build.yml

@@ -35,7 +35,7 @@ jobs:
         if: steps.changed-files.outputs.any_changed == 'true'
         run: nix build
 
-      - uses: actions/upload-artifact@v2
+      - uses: actions/upload-artifact@v3
         if: steps.changed-files.outputs.any_changed == 'true'
         with:
           name: headscale-linux