Add spec for product pages translation
Revert "Added default_scope to avoid N+1 problem"

This reverts commit f38be5fe51d42323a0b3cc9fd1dbe4ff70592ac4.

This causes translations not to work anymore as proven by regression spec added:
https://github.com/spree/spree_i18n/commit/f260ff7cd660c7adc94a500e4035025e6922405c