Remove TracingUtil and its Smack dependency

[bgrozev]

TracingUtil bridged an XMPP <traceparent> stanza extension into an OpenTelemetry span/context. It depended directly on jitsi-xmpp-extensions and (transitively) the jitsi-patched smack-core fork, neither of which are available on Maven Central.

jicoco-tracing is listed under the central-modules profile, which the release-to-Central job builds without the non-central repositories enabled — so the release failed trying to resolve smack-core:4.4.8-jitsi-4:

https://github.com/jitsi/jicoco/actions/runs/30963018171/job/92171674688

This removes TracingUtil and the now-unused dependencies. Callers should inline the IQ-to-span-context logic themselves.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 35.54%. Comparing base (d754d3d) to head (92e5aaa).

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #241      +/-   ##
============================================
- Coverage     35.99%   35.54%   -0.45%     
+ Complexity      167      163       -4     
============================================
  Files            39       38       -1     
  Lines          1439     1429      -10     
  Branches        144      143       -1     
============================================
- Hits            518      508      -10     
  Misses          888      888              
  Partials         33       33              

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[damencho]

jenkins test this please