use plugin filename to support non turtlebot sdf/urdf

[proioxrobots]

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Basic Info

Info	Please fill out this column
Ticket(s) this addresses
Primary OS tested on	Ubuntu
Robotic platform tested on	gazebo simulation

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Description of contribution in a few bullet points

Use diff drive plugin filename instead of values to support non-turtlebot sdf.
If there are other diff_drive plugins that can be added, we can create a list.

Description of documentation updates required from your changes

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Future work that may be required in bullet points

For Maintainers:

• Check that any new parameters added are updated in navigation.ros.org
• Check that any significant change is added to the migration guide
• Check that any new functions have Doxygen added
• Check that any new features have test coverage
• Check that any new plugins is added to the plugins page
• If BT Node, Additionally: add to BT's XML index of nodes for groot, BT package's readme table, and BT library lists