Remoe translations of values-mcc310-mnc260

Since values-mcc310-mnc260/strings.xml has been removed,
its translations should also be removed. Otherwise they're
shadowing values/strings.xml.

Bug: 62213418
Test: manual - now R.string.wfcOperatorErrorAlertMessages
               is the same as in values/strings.xml
Change-Id: I1e1058925fc22f507bc8009c423d86ecb22741c1