Update E2E jobs to run SDG on different filetypes

[khaledsulayman]

Currently, the e2e only tests on markdown. We should consider testing on PDF now that we support it. Unless we want to replace the markdown test in e2e, our only option right now might be to run SDG once with a markdown doc and once with a pdf, which could add some overhead to the e2es.

Alternatively, it looks like docling supports running on multiple documents of mixed types. Once #334 is done, we might be able to simply put one document of each type that we support and run on all of them.