refactor(ssh): consolidate real_ssh into ssh, remove duplication

real_ssh was a separate service name pointing to the same template and
behaviour as ssh. Merged them: ssh is now the single real-OpenSSH service.

- Rename templates/real_ssh/ → templates/ssh/
- Remove decnet/services/real_ssh.py
- Deaddeck archetype updated: services=["ssh"]
- Merge test_real_ssh.py into test_ssh.py (includes deaddeck + logging tests)
- Drop decnet.services.real_ssh from test_build module list

templates/cowrie/honeyfs/etc/motd

@@ -0,0 +1,26 @@
+
+ * Documentation:  https://help.ubuntu.com
+ * Management:     https://landscape.canonical.com
+ * Support:        https://ubuntu.com/advantage
+
+  System information as of Mon Jan 15 09:12:44 UTC 2024
+
+  System load:  0.08               Processes:             142
+  Usage of /:   34.2% of 49.10GB   Users logged in:       0
+  Memory usage: 22%                IPv4 address for eth0: 10.0.1.5
+  Swap usage:   0%
+
+ * Strictly confined Kubernetes makes edge and IoT secure. Learn how MicroK8s
+   just raised the bar for K8s security.
+
+     https://ubuntu.com/engage/secure-kubernetes-at-the-edge
+
+Expanded Security Maintenance for Applications is not enabled.
+
+0 updates can be applied immediately.
+
+Enable ESM Apps to receive additional future security updates.
+See https://ubuntu.com/esm or run: sudo pro status
+
+
+Last login: Sun Jan 14 23:45:01 2024 from 10.0.0.1