Trace reporting not working when setting reporter-queue-size to any value different than the default.

[vvasilevbosch]

When setting reporter-queue-size to any different value than default '4096', Tracer.reconfigure is called, which reinstantiates kamon.trace.Tracer#_spanBuffer but kamon.trace.Tracer#_onSpanFinish keeps reference to its old value, which is what causes this issue. The _onSpanFinish lambda should be updated with the new reference of _spanBuffer

Kamon/core/kamon-core/src/main/scala/kamon/trace/Tracer.scala

Line 60 in c3f0655

private val _onSpanFinish: Span.Finished => Unit = _spanBuffer.offer

https://github.com/kamon-io/Kamon/blob/c3f065517f046f6feffb47652a9ac91d664f160b/core/kamon-core/src/main/scala/kamon/trace/Tracer.scala#L459C1-L465

  def reconfigure(newConfig: Config): Unit = synchronized {
    //......
      if(_traceReporterQueueSize != traceReporterQueueSize) {
        // By simply changing the buffer we might be dropping Spans that have not been collected yet by the reporters.
        // Since reconfigures are very unlikely to happen beyond application startup this might not be a problem.
        // If we eventually decide to keep those possible Spans around then we will need to change the queue type to
        // multiple consumer as the reconfiguring thread will need to drain the contents before replacing.
        _spanBuffer = new MpscArrayQueue[Span.Finished](traceReporterQueueSize)
      }
    //......
  }