I believe we can agree that this specific use in the Italian press is an attempt to sound "English" (many think it is "cool", "modern" - Italians are known to be xenophilous after all), hence we should call it an "anglicism".
Specifically it is a diminutive form of a given name (this is called a "hypocorism") and is typically used as a "term of endearment" ("vezzeggiativo", in Italian). Of course, such diminutive terms of endearment can also be used sarcastically as derogatory terms, as in the examples mentioned in the question.
I ignore the origin of the suffix "-y" as a diminutive (a "hypocorism by reduction"), some say it is of German origin, egreg suggested in his comment above it is of French origin. I suspect it might be common to more than one language.
Some reading (links from english.stackexchange):
On the origin of the English diminutive suffix -y, -ie, The Free Library
Etimology of suffix -y, Wiktionary