message: [test] increase the waiting time in dbus tests
  We found failed cases where the Thread network has not been formed yet.
  Increase the timeout to make it more stable.
diff: @@ -99,7 +99,7 @@ send "commissioner joiner add * ABCDEF\r\n"
  expect "Done"
  wait
  EOF
  - sleep 7
  + sleep 15
  sudo dbus-send --system --dest=io.openthread.BorderRouter.wpan0 \
  --type=method_call --print-reply /io/openthread/BorderRouter/wpan0 \
  io.openthread.BorderRouter.JoinerStart \
  