[Tracker] Apply KMeans C ABI Breaking Changes in 26.08

[tarang-jain]

#2015 adds a C ABI breaking change into 26.06, which must be incorporated into the main structs and functions for KMeans when ABI breaking changes are allowed (26.08). TODO list:

• Remove _v2 versions from C tests
• Remove the _v2 functions from C header
• Remove template ParamsT for cuvsKmeansParamsCreate and cuvsKmeansParamsDestroy
• Remove docs / notes in the codebase that track this
• We must also deprecate the inertia_check parameter from the python API