beaker/server: fix client config quoting

I misunderstood what the |quote filter in Ansible does. It turns out
bkr's config parser doesn't even handle escaped quotes correctly
anyway(!) so for now we will have to just assume the admin username and
password don't contain any quote characters.

roles/beaker/server/templates/root/beaker-client-config.j2

@@ -1,4 +1,4 @@
 HUB_URL = "http://localhost/bkr"
 AUTH_METHOD = "password"
-USERNAME = {{ beaker_server_admin_user|quote }}
-PASSWORD = {{ beaker_server_admin_pass|quote }}
+USERNAME = "{{ beaker_server_admin_user }}"
+PASSWORD = "{{ beaker_server_admin_pass }}"