Update prosody config for JaaS customers

doc/debian/jitsi-meet-prosody/prosody.cfg.lua-jvb.example

     }
     authentication = "token"
     app_id = "jitsi";
-    asap_key_server = "https://jaas-public-keys.jitsi.net/vpaas/prod-8x8"
+    asap_key_server = "https://jaas-public-keys.jitsi.net/jitsi-components/prod-8x8"
     asap_accepted_issuers = { "jaas-components" }
     asap_accepted_audiences = { "jigasi.jitmeet.example.com" }