Preprocess: Patch over missing iir_params

[msilvafe]

We've identified the reason for missing iir params and have put some fixes in place so that it doesn't happen in the future. However we need a fix in place to use/ignore this data that. The short term solution is to add a preprocess method that handles the behavior when iir_params are missing (either cut those detectors or fill them with a config specified default if its determined that its safe). The longer term solution will be an attachable obsdb and custom loader that applies a fix function. This issue and the short/long-term solutions are discussed in more detail in issue #969 . This issue is for tracking the short-term preprocess solution.

[msilvafe]

Its not going to be possible to cut all detectors since that'll fail at the further steps in the pipeline so would require us to add some sort of check after each pipe.select step which would exit the pipe if dets were cut to zero. That sounds like a reasonable thing to add but is a bit more infrastructure. A simpler short term solution which works with the current preproc structure is to have a logic check for what platform/wafer/time range etc is valid to fill with defaults and fill those.