Extend URL stripping in Simple selection builder to non EN projects

[audiodude]

Currently there is code in the Simple Selection validator that strips the following prefixes from article names:

https://en.wikipedia.org/wiki/
https://en.wikipedia.org/w/index.php?title=

This is a courtesy to prevent invalid article names from making it to the ZIM farm, however it should be obvious that this only works for en.wikipedia.org. Instead, we should use the project name associated with the builder to strip.