Fix controller dependencies

[christophfroehlich]

We only use JTC or forward_command_controller for the demos, the specializations got removed with ros-controls/ros2_controllers#2016

[christophfroehlich]

@Mergifyio backport kilted jazzy humble

[mergify]

backport kilted jazzy humble

✅ Backports have been created

Details

• #838 Fix controller dependencies (backport #837) has been created for branch kilted
• #839 Fix controller dependencies (backport #837) has been created for branch jazzy
• #840 Fix controller dependencies (backport #837) has been created for branch humble but encountered conflicts

Cherry-pick of 54addf2 has failed:

On branch mergify/bp/humble/pr-837
Your branch is up to date with 'origin/humble'.

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Unmerged paths:
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	both modified:   gz_ros2_control_demos/package.xml

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