Have confetty show correct trace more easily

In some scenarios, the quitconfetty will overwrite the
stack trace.

Get the relevant trace before trying the quitconfetty, then print
the saved trace.

confluent_client/bin/confetty

@@ -1024,11 +1024,12 @@ if __name__ == '__main__':
         errcode = e.errorcode
     except Exception as e:
         import traceback
+        excinfo = traceback.print_exc()
         try:
             quitconfetty()
         except Exception:
             pass
-        traceback.print_exc()
+        print(excinfo)
     finally:
         if deadline and os.times()[4] < deadline:
             sys.stderr.write('[Exited early, hit enter to continue]')