String export: remove XLIFF file path rewrite

This was added to work around the file path change, causing the XLIFF to completely change
https://github.com/mozilla-l10n/mozilla-vpn-client-l10n/pull/179/files#diff-8ab33a758d9320e691f7846c6fb40418050539d40965de2413f34e23cbbf8c0fR50

We should remove it, if we move to a different system and we migrate existing strings to it
https://github.com/mozilla-mobile/mozilla-vpn-client/issues/1331