Fix jitsi ghcr.io registry, fix keila tz writable volume

- jitsi: stable tags moved to ghcr.io/jitsi/* (no longer on Docker Hub)
- keila: mount emptyDir at /opt/app/lib/tz-0.28.2/priv so the tz
  library can write timezone data (TZ_AUTOUPDATE env var doesn't work,
  it's Elixir app config not env-driven)

jitsi/versions/stable/deployment-prosody.yaml

@@ -22,7 +22,7 @@ spec:
           type: RuntimeDefault
       containers:
         - name: jitsi-prosody
-          image: jitsi/prosody:stable-11248-2
+          image: ghcr.io/jitsi/prosody:stable-11248-2
           ports:
             - name: xmpp-c2s
               containerPort: 5222