Move p_astro calculation to individual detection pipelines
An automatic GCN Preliminary Notice for S190517h was not issued due to the failure of gstlal to upload a 90Mbyte ranking_data.xml.gz file for the preferred event even after 5 automatic retries. However, ~2GByte of ranking data where uploaded for a subset of the 21 associated non-preferred G-events.
To avoid a repeat of this problem, gstlal should instead upload the derived p_astro.json file, which is O(10^6) times smaller, and obviate the need for gwcelery to download the ranking data, compute p_astro and upload the resulting json file.
Note, during a transition period for all of the low-latency detection pipelines to provide their best reviewed p_astro calculations directly to GraceDB the simplified approximate calculationshould be calculated by gwcelery and made available to Advocates as a backup.