cmd/k8s-operator: generate static kube manifests from the Helm chart. (#10436)

* cmd/k8s-operator: generate static manifests from Helm charts

This is done to ensure that there is a single source of truth
for the operator kube manifests.
Also adds linux node selector to the static manifests as
this was added as a default to the Helm chart.

Static manifests can now be generated by running
`go generate tailscale.com/cmd/k8s-operator`.

Updates tailscale/tailscale#9222

Signed-off-by: Irbe Krumina <irbe@tailscale.com>

.github/workflows/test.yml

@@ -429,7 +429,7 @@ jobs:
       uses: actions/checkout@v4
     - name: check that 'go generate' is clean
       run: |
-        pkgs=$(./tool/go list ./... | grep -v dnsfallback)
+        pkgs=$(./tool/go list ./... | grep -Ev 'dnsfallback|k8s-operator')
         ./tool/go generate $pkgs
         echo
         echo