Does the ruling of permissibility for a girl to reside in university housing, if those in charge of it are trustworthy, also apply to a disbelieving country, or is it restricted to Islamic countries?

The basic principle is that a disbelieving country is not safe. A Muslim woman desiring to live in university housing in the land of the disbelievers must verify the safety and suitability of the accommodation for her. Otherwise, she should not reside in housing where she will be exposed to temptations and the dangers of corruption of religion and morals.