Github CI on rolling/iron missing tests which causes build farm failures

[Ryanf55]

CI missed a regression that the ROS build farm caught this. The backport to humble caught the failure. I'm not sure what is causing the inconsistency.

-- Generating done
CMake Generate step failed.  Build files cannot be regenerated correctly.
---
--- stderr: grid_map_costmap_2d
CMake Error at /opt/ros/iron/share/ament_cmake_gtest/cmake/ament_add_gtest_executable.cmake:50 (add_executable):
  Target "grid_map_costmap_2d-test" links to target
  "nav2_costmap_2d::nav2_costmap_2d_core" but the target was not found.
  Perhaps a find_package() call is missing for an IMPORTED target, or an
  ALIAS target is missing?
Call Stack (most recent call first):
  /opt/ros/iron/share/ament_cmake_gtest/cmake/ament_add_gtest_executable.cmake:37 (_ament_add_gtest_executable)
  /opt/ros/iron/share/ament_cmake_gtest/cmake/ament_add_gtest.cmake:68 (ament_add_gtest_executable)
  test/CMakeLists.txt:1 (ament_add_gtest)


CMake Error at /opt/ros/iron/share/ament_cmake_gtest/cmake/ament_add_gtest_executable.cmake:50 (add_executable):
  Target "costmap-2d-ros-test" links to target
  "nav2_costmap_2d::nav2_costmap_2d_core" but the target was not found.
  Perhaps a find_package() call is missing for an IMPORTED target, or an
  ALIAS target is missing?
Call Stack (most recent call first):
  /opt/ros/iron/share/ament_cmake_gtest/cmake/ament_add_gtest_executable.cmake:37 (_ament_add_gtest_executable)
  /opt/ros/iron/share/ament_cmake_gtest/cmake/ament_add_gtest.cmake:68 (ament_add_gtest_executable)
  test/CMakeLists.txt:10 (ament_add_gtest)

Originally posted by @Ryanf55 in #448 (comment)

[Ryanf55]

Perhaps related to using testing images in CI, but the build farm using stable.
https://docs.ros.org/en/rolling/Installation/Testing.html#debian-testing-repository