Fix ringdown and endtime for bypass

Will fill in later, but got some bugs fixed and minor refactors done.

A separate branch should be made for spiir-O4-EW-development first to fix snr series over in postcoh. The timestamp (epoch) doesn't correspond to the samples by a factor of the template ringdown. That doesn't have any significant impact on skymaps given that ringdown is a fraction of a second, and all the snr series are offset by the same amount (i.e. our skymaps are off by the amount earth rotates in a fraction of a second, if I'm not mistaken).

Since bypass didn't have that same bug (it has other bugs, don't worry, fixed at least one to do with end_time in this branch), its snr series wound up throwing off our skymaps.