monitoring: probe XMPP c2s with a plain connect

blackbox_exporter matches query_response line by line, and ejabberd
writes its stream features and <proceed/> without newlines, so the
STARTTLS dialogue always timed out and the probe alert fired while
XMPP was fine. Port 5222 gets a TCP connect; the certificate is still
checked through direct TLS on 5223.

Assisted-by: Claude:opus-5-5

ansible/roles/monitoring/templates/blackbox.yml.j2

@@ -25,14 +25,3 @@ modules:
     tcp:
       preferred_ip_protocol: ip4
   # XMPP client port: stream header, STARTTLS, then the certificate
-  xmpp_starttls:
-    prober: tcp
-    timeout: 10s
-    tcp:
-      preferred_ip_protocol: ip4
-      query_response:
-        - send: "<?xml version='1.0'?><stream:stream to='asxp.io' xmlns='jabber:client' xmlns:stream='http://etherx.jabber.org/streams' version='1.0'>"
-        - expect: "urn:ietf:params:xml:ns:xmpp-tls"
-        - send: "<starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>"
-        - expect: "<proceed"
-        - starttls: true