Fix: preserve planar joint suffix in Ros2ControlManager (Fixes #3594)

[saumanraaj]

Description

This PR fixes incorrect parsing of claimed interfaces in moveit_ros_control_interface::Ros2ControlManager.

Problem:
Planar (and other multi-DOF) joints expose variable names with an extra segment (e.g., base_joint/x/position, base_joint/y/position, base_joint/theta/position). The current helper:

std::string parseJointNameFromResource(const std::string& claimed_interface)
{
  const auto index = claimed_interface.find('/');
  if (index == std::string::npos)
    return claimed_interface;
  return claimed_interface.substr(0, index);
}

splits at the first /, turning base_joint/x/position into base_joint, which drops the /x (or /y, /theta) component. As a result, Ros2ControlManager fails to find the appropriate controller, even when it exists.

Fix:
Change the parsing to strip only the final interface segment (e.g., /position, /velocity, /effort) and preserve intermediate suffixes for multi-DOF joints:

// Strip only the final interface segment (e.g., /position) to preserve
// multi-DOF suffixes such as /x, /y, /theta for planar and floating joints.
const auto last = claimed_interface.rfind('/');
if (last == std::string::npos)
  return claimed_interface;
return claimed_interface.substr(0, last);

This makes:

• joint1/position → joint1 (unchanged behavior for single-DOF)
• base_joint/x/position → base_joint/x
• base_joint/theta/velocity → base_joint/theta

Related issue: Fixes #3594.

Why safe:
The change is localized, backward-compatible for single-DOF joints, and aligns with MoveIt’s planar joint variable naming (name/x, name/y, name/theta).

Manual check (optional):
Using the Mobile Base + Arm tutorial (with moveit_ros_control_interface/Ros2ControlManager), controllers advertising base_joint/{x,y,theta}/position are now correctly matched.

---

Checklist

• Required by CI: Code is auto-formatted using [clang-format](http://moveit.ros.org/documentation/contributing/code)
  (ran ament_clang_format / verified formatting)
• Extend the tutorials / documentation [reference](http://moveit.ros.org/documentation/contributing/)
  N/A for this targeted fix, but happy to add a note if desired.
• Document API changes relevant to the user in [MIGRATION.md](https://github.com/moveit/moveit2/blob/main/MIGRATION.md)
  No API change; behavior fix only.
• Create tests, which fail without this PR [reference](https://moveit.picknik.ai/humble/doc/examples/tests/tests_tutorial.html)
  If maintainers want, I can add small parser unit tests:
  • "joint1/position" → "joint1"
  • "base_joint/x/position" → "base_joint/x"
  • "base_joint/theta/velocity" → "base_joint/theta"
• Include a screenshot if changing a GUI
  N/A
• While waiting for review, I will help review [another open pull request](https://github.com/moveit/moveit2/pulls)

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Notes for reviewers

• If there are other code paths parsing claimed interfaces, I can unify them on the same “strip-last-segment” helper for consistency.