message: [test] fix dbus client checks
  The rloc16 value can be zero, use 0xffff for an invalid value instead.
  The parition id a radmon value so it shall not be checked.
diff: @@ -120,8 +120,8 @@ int main()
  if (aError == OTBR_ERROR_NONE)
  {
  std::string name;
  - uint64_t extAddress;
  - uint16_t rloc16;
  + uint64_t extAddress = 0;
  + uint16_t rloc16 = 0xffff;
  uint8_t routerId;
  std::vector<uint8_t> networkData;
  std::vector<uint8_t> stableNetworkData;
  @@ -161,9 +161,8 @@ int main()
  assert(api->RemoveOnMeshPrefix(onMeshPrefix.mPrefix) == OTBR_ERROR_NONE);
  api->FactoryReset(nullptr);
  assert(api->GetNetworkName(name) == OTBR_ERROR_NONE);
  - assert(rloc16 != 0);
  + assert(rloc16 != 0xffff);
  assert(extAddress != 0);
  - assert(partitionId != 0);
  assert(routerId == leaderData.mLeaderRouterId);
  assert(!networkData.empty());
  assert(childTable.empty());
  