[lldb][NFCI] Remove typedef for TypeCategoryMap::ValueSP (#65555)

lldb already has a `ValueSP` type. This was confusing to me when reading
TypeCategoryMap, especially when `ValueSP` is not qualified. From first
glance it looks like it's referring to a
`std::shared_ptr<lldb_private::Value>` when it's really referring to a
`std::shared_ptr<lldb_private::TypeCategoryImpl>`.