cmd/{containerboot,k8s-operator}: reissue auth keys for broken proxies (#16450)

Adds logic for containerboot to signal that it can't auth, so the
operator can reissue a new auth key. This only applies when running with
a config file and with a kube state store.

If the operator sees reissue_authkey in a state Secret, it will create a
new auth key iff the config has no auth key or its auth key matches the
value of reissue_authkey from the state Secret. This is to ensure we
don't reissue auth keys in a tight loop if the proxy is slow to start or
failing for some other reason. The reissue logic also uses a burstable
rate limiter to ensure there's no way a terminally misconfigured
or buggy operator can automatically generate new auth keys in a tight loop.

Additional implementation details (ChaosInTheCRD):

- Added `ipn.NotifyInitialHealthState` to ipn watcher, to ensure that
  `n.Health` is populated when notify's are returned.
- on auth failure, containerboot:
  - Disconnects from control server
  - Sets reissue_authkey marker in state Secret with the failing key
  - Polls config file for new auth key (10 minute timeout)
  - Restarts after receiving new key to apply it

- modified operator's reissue logic slightly:
  - Deletes old device from tailnet before creating new key
  - Rate limiting: 1 key per 30s with initial burst equal to replica count
  - In-flight tracking (authKeyReissuing map) prevents duplicate API calls
    across reconcile loops

Updates #14080

Change-Id: I6982f8e741932a6891f2f48a2936f7f6a455317f


(cherry picked from commit 969927c47c3d4de05e90f5b26a6d8d931c5ceed4)

Signed-off-by: Tom Proctor <tomhjp@users.noreply.github.com>
Co-authored-by: chaosinthecrd <tom@tmlabs.co.uk>

cmd/k8s-operator/testutils_test.go

@@ -529,7 +529,7 @@ func expectedSecret(t *testing.T, cl client.Client, opts configOpts) *corev1.Sec
 		AcceptDNS:           "false",
 		Hostname:            &opts.hostname,
 		Locked:              "false",
-		AuthKey:             new("secret-authkey"),
+		AuthKey:             new("new-authkey"),
 		AcceptRoutes:        "false",
 		AppConnector:        &ipn.AppConnectorPrefs{Advertise: false},
 		NoStatefulFiltering: "true",
@@ -859,7 +859,7 @@ func (c *fakeTSClient) CreateKey(ctx context.Context, caps tailscale.KeyCapabili
 		Created:      time.Now(),
 		Capabilities: caps,
 	}
-	return "secret-authkey", k, nil
+	return "new-authkey", k, nil
 }
 
 func (c *fakeTSClient) Device(ctx context.Context, deviceID string, fields *tailscale.DeviceFieldsOpts) (*tailscale.Device, error) {