Fix fallback limits for prismatic joints in Ruckig smoothing

[nk-pavan-official]

Description

This PR fixes the fallback limits used for prismatic joints when joint limits are not defined.

Previously, prismatic joints used the same default values as revolute joints, which are in angular units. This could result in incorrect fallback limits for linear joints.

This PR:

*Adds separate default limits for prismatic joints.
*Selects the correct fallback based on the joint type.
*Updates the warning messages with the correct units.
*Adds tests to verify the new behavior.

Fixes #3781

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

[nk-pavan-official]

I have opened a PR for this issue: #3783

Looking forward to any feedback. Thanks!
#3783 (comment)