> string theory made numerous testable predictions of what particles LHC should detect at different energy levelsNo, it didn't. Particular supersymmetric extensions to the Standard Model made testable predictions of what particles the LHC should detect at different energy levels, none of which have panned out.
String theorists like to take credit for those predictions (or at least they did until the predictions became notorious for their wrongness) because they claim that string theory is what justifies those particular supersymmetric extensions to the Standard Model. That doesn't mean we should let them get away with it.