Translation CI: Exclude android strings from the legacy branch

I just realised that the translation CI is including torbrowser_strings.xml from the legacy 13.5 branch, even though we have no legacy android build.

This will mean that android strings from 13.5 will persist longer than necessary.

@pierov We could either:

1. Drop the commit that includes torbrowser_strings.xml in the 13.5 branch, or
2. Create an exception for torbrowser_strings.xml in the translation CI script.

Which would you prefer?