Remove unnecessary coincidence_far.json file creation

There seems to be some unnecessary lines of codes that are causing errors whenever calc_signif_gracedb is called multiple times in close succession: https://git.ligo.org/lscsoft/raven/-/blob/master/ligo/raven/search.py#L558-561

This code creates a file we do nothing with, upload a different instance directly to GraceDB anyways. os.remove() is being called after this file has been removed by another instance of the function. See the error here: https://sentry.io/organizations/ligo-caltech/issues/3230621935/events/e801b3191de34b228de12edcd52e7dab/?environment=test&project=1425216

We can likely remove the indentation and simplify this portion.