Remove InvalidNameReuse exception in favor of in InvalidModel

[matthewfeickert]

In relation to Issue #2059, @lorenzennio was wanting to handle this via raising InvalidNameReuse though he and @kratsg pointed out that what is actually happening is maybe a better use of InvalidModel. InvalidNameReuse was added in PR #209 though in the current uses of InvalidNameReuse

pyhf/src/pyhf/parameters/utils.py

Lines 42 to 45 in 1191f66

	if len(combined_paramset[k]) != 1:
	raise exceptions.InvalidNameReuse(
	f"Multiple values for '{k}' ({list(combined_paramset[k])}) were found for {paramset_name}. Use unique modifier names when constructing the pdf."
	)

@kratsg thinks this should just be covered by InvalidModel.

If this actually is an invalid model then InvalidNameReuse can be removed everywhere in the code and InvalidModel can be used instead.