URDF parsing no longer strips filepaths by default.

This default forces users to use the `spec.assets` dictionary or to do other filepath gymnastics when loading URDF. Instead we encourage users to just modify file paths directly if necessary.

PiperOrigin-RevId: 899009853
Change-Id: I4bb84606a95b65be79ccc77ccbe78062d6de8773

src/xml/xml.cc

@@ -296,7 +296,6 @@ mjSpec* SpecFromXML(std::string_view xml, std::string_view dir,
 
       // set reasonable default for parsing a URDF
       // this is separate from the Parser to allow multiple URDFs to be loaded.
-      spec->strippath = true;
       spec->compiler.fusestatic = true;
       spec->compiler.discardvisual = true;