Look at the prototype:
native create_entity(szClassname[]);
It's not a
native create_entity(const szClassname[]);
That is why you should not use const keyword for your global. Just omit it in your example.
Using static has no sense here because of a global scope. AFAIK, global static vars are used to deny amx/x engine to access this var. It's hard to imagine for me an example when it's vital to use static declaration in global scope.