Globally selected alternatives with the same priority do not result in ambiguous dependency

Currently, the priority is ignored and the index is used:
https://github.com/weld/core/blob/2.4/impl/src/main/java/org/jboss/weld/bootstrap/enablement/GlobalEnablementBuilder.java#L155

I believe this is a regression introduced when we tried to work around the spec issue mentioned in CDI-437 (see also WELD-1660). And later when we implemented the "priority scaling" (in the context of WELD-2000) we forgot to use Item#getPriority() again.