get_found_injections incompatible with newest injection format

We edited get_found_injections to be consistent with the O1+O2+O3+O4a mixture injections which used semianalytic sensitivity estimates for O1, O2, and O3. The new injections with real O4a sensitivity have a format which is different than the previous injection sets. The FARs are stored in keys that are formatted {o3,o4}_{pipeline}_far, so this will require another if statement and some additional logic in get_found_injections. @colm.talbot