Remove timeseries from disconnected fibers

I recently learned from @hagikent that timeseries from all four fibers is being saved to the NWB files, even though in most cases (maybe all cases so far?) not all fibers patch cables are actually connected to implanted fibers in the brain. This means that some of the saved timeseries just represent ambient light, not physiology data.

The fiber bundle currently has four fibers, but only a subset of them are generally connected to implanted fibers in the brain.

This has two major disadvantages:
1) It's inefficient from a storage standpoint. The NWB files will be larger than necessary.
2) It's confusing for users. It would be natural for a user to make the assumption that all four timeseries in the NWB file represent physiology data.

Going forward, we should identify which fibers are disconnected during processing and avoid packaging the corresponding timeseries in the NWB file. We should be able to rely on the metadata to get this information, which means that solving this issue will be dependent on the metadata containing reliable information about which fibers are connected. I will create a corresponding issue in the metadata mapper repo to accomplish this and will link it here.