make/cluster.sh: speedup etcd by using --unsafe-no-fsync

Using --unsafe-no-fsync is OK for development deployments of etcd [1].
etcd relies on fsync for its consensus protocol.

 [1]: etcd-io/etcd#11946
 [2]: https://etcd.io/docs/v3.5/tuning/#disk
 [3]: https://etcd.io/docs/v3.5/faq/

Signed-off-by: Maël Valais <mael@vls.dev>
Co-authored-by: Tim Ramlot <42113979+inteon@users.noreply.github.com>

make/config/kind/v1beta2.yaml

@@ -13,5 +13,9 @@ kubeadmConfigPatches:
       name: config
     networking:
       serviceSubnet: 10.0.0.0/16
+    etcd:
+      local:
+        extraArgs:
+          unsafe-no-fsync: "True"
 nodes:
   - role: control-plane