Remove plugins from export set (backport #3227)

[mergify]

Description

Plugins that are intended to be loaded by classloader or pluginlib should not be in export sets that ament_export_targets is called on. This can cause plugins to fail to load.

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This is an automatic backport of pull request #3227 done by Mergify.

[mergify]

Cherry-pick of b5eb4de has failed:

On branch mergify/bp/humble/pr-3227
Your branch is up to date with 'origin/humble'.

You are currently cherry-picking commit b5eb4deb3.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   moveit_core/CMakeLists.txt
	both modified:   moveit_kinematics/CMakeLists.txt
	both modified:   moveit_kinematics/cached_ik_kinematics_plugin/CMakeLists.txt
	both modified:   moveit_ros/move_group/CMakeLists.txt

no changes added to commit (use "git add" and/or "git commit -a")

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