Fix error message text about invalid servo parameters (backport #2769)

[mergify]

Description

Was debugging something and realized this error message is swapped.

I'll add this later when I'm on a dev computer, but looks like we should also add a check for if ((servo_params.command_out_type == "std_msgs/Float64MultiArray") && !servo_params.publish_joint_positions && !servo_params.publish_joint_velocities) - The previous check would not trigger that as it is specific to Float64 type.

Checklist

• Required by CI: Code is auto formatted using clang-format
• Extend the tutorials / documentation reference
• Document API changes relevant to the user in the MIGRATION.md notes
• Create tests, which fail without this PR reference
• Include a screenshot if changing a GUI
• While waiting for someone to review your request, please help review another open pull request to support the maintainers

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This is an automatic backport of pull request #2769 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of df78880 has failed:

On branch mergify/bp/iron/pr-2769
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	both modified:   moveit_ros/moveit_servo/src/servo.cpp

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[github-actions]

This PR is stale because it has been open for 45 days with no activity. Please tag a maintainer for help on completing this PR, or close it if you think it has become obsolete.