Revert "create a span"

This reverts commit afd509b.

Author: mabdinur

ddtrace/contrib/internal/futures/threading.py

@@ -38,8 +38,4 @@ def _wrap_execution(ctx: Tuple[Optional[Context], Optional[Context]], fn, args,
         ddtrace.tracer.context_provider.activate(ctx[0])
     if ctx[1] is not None:
         core.dispatch("threading.execution", (ctx[1],))
-
-    with ddtrace.tracer.trace("threading.execution"):
-        # This ensures all the spans created by the target function
-        # are included in the same trace
-        return fn(*args, **kwargs)
+    return fn(*args, **kwargs)