refactor: 💥 is_XXX customization points for representation types removed

example/storage_tank.cpp

@@ -40,12 +40,6 @@ import mp_units;
 #include <mp-units/systems/si.h>
 #endif
 
-// allows standard gravity (acceleration) and weight (force) to be expressed with scalar representation
-// types instead of requiring the usage of Linear Algebra library for this simple example
-template<class T>
-  requires mp_units::is_scalar<T>
-constexpr bool mp_units::is_vector<T> = true;
-
 namespace {
 
 using namespace mp_units;