docker (prosody-e2e): update Prosody's conf: Due to mod_privilege and PAM implementation in Libervia Pubsub, permissions have been udpated in `prosody.cfg.lua`, with the new `iq` permission and namespace delegation needed for PAM. `"urn:xmpp:delegation:2:bare:disco#info:*"` namespace delegation was also missing. rel 365

this certificates are used to enable TLS during tests. Those must be the same as in
backend_e2e (they are generated there)