Fix incorrect parameters to Trace::TraceId.new

An extra argument is needed by finagle-thrift v1.3.x; this was broken by commit 22a12cff2214e39fe948bd2c1b4a4790e0b5987c
Sure, we could take it in as a parameter to get_or_create_trace_id, e.g.

   get_or_create_trace_id(env, opts = ::Trace::Flags::EMPTY)
      ...
      trace_parameters << opts