[stable/2023.1] fix: allow ssh login for nova user in nova-ssh image (#1249)

This is an automated cherry-pick of #1246
/assign mnaser
diff --git a/zuul.d/container-images/nova-ssh.yaml b/zuul.d/container-images/nova-ssh.yaml
index 3650306..df638aa 100644
--- a/zuul.d/container-images/nova-ssh.yaml
+++ b/zuul.d/container-images/nova-ssh.yaml
@@ -46,6 +46,7 @@
           build_args:
             - "RELEASE={{ zuul.branch | replace('stable/', '') }}"
             - PROJECT=nova
+            - SHELL=/bin/bash
           tags:
             - "{{ zuul.branch | replace('stable/', '') }}"
     files: &container_image_files