caddy-frontend: Run kedifa-updater with prepare

During buildout run no network communication is required in order to prepare
fallback certificates, so call kedifa-updater with --prepare-only

software/caddy-frontend/buildout.hash.cfg

@@ -30,7 +30,7 @@ md5sum = d62aefe002ec13875924e4c219914795
 
 [template-slave-list]
 filename = templates/apache-custom-slave-list.cfg.in
-md5sum = 57f562311bac6dbf85cd35891eaa6743
+md5sum = e0d0c9fc7d4bf95dac580bbc1d2a4d93
 
 [template-slave-configuration]
 filename = templates/custom-virtualhost.conf.in

software/caddy-frontend/templates/apache-custom-slave-list.cfg.in

@@ -446,7 +446,7 @@ hash-files = ${buildout:directory}/software_release/buildout.cfg
 recipe = plone.recipe.command
 # unfortunately slapos.cookbook:wrapper does not return generated wrapper path
 # so it is needed to access it via service directory globbing
-command = {{ service_directory }}/kedifa-updater* --once
+command = {{ service_directory }}/kedifa-updater* --prepare-only
 update-command = ${:command}
 
 [kedifa-updater-mapping]