Add UTF-16 to expected default encoding list

Hey @brianmario, it looks like these tests are failing on master too. You fixed them in a branch commit, 43037a6ded58946861bd25e771fe53465c05a270, but we should probably just merge the fix in to master first. I'm not sure what change triggered a output differences. Maybe since I'm using icu4c 54.1 locally now?