CI fix - [ROS2] Restrict Eigen plugin definitions to only targets linking against grid_map_core

[bperseghetti]

CI Fix to be able to merge the work in #519

Related to: https://github.com/ros-navigation/navigation2/issues/5103

[mergify[bot]]

⚠️ The sha of the head commit of this PR conflicts with #519. Mergify cannot evaluate rules on this PR. ⚠️

[Ryanf55]

Latest CI:

E: Unable to locate package ros-rolling-octomap-server
ERROR: the following rosdeps failed to install
  apt: command [apt-get install -y ros-rolling-octomap-server] failed

docker run --net host  -it ros:rolling bash
apt update 
rosdep update
rosdep resolve octomap-server
>>> ERROR: no rosdep rule for 'octomap-server'
apt install -y ros-

>>> E: Unable to locate package ros-rolling-octomap-server

I'll keep working this on my branch. I don't seem to have push authority to fixup changes. https://github.com/Ryanf55/grid_map/pull/5