Retire lscsoft/gwcelery p_astro calculation for pycbc events when pipeline calculation is available

PyCBC Live is developing a tool that computes relative probabilities of source types based on template chirp mass and effective distances. The probabilities are available for each G event as a json file and as a pie chart in the GraceDB page. This is to be combined with a calculation of p_astro/p_terr in the pycbc pipeline to replace the calculation being done for PyCBC in lscsoft/p_astro.

• PyCBC is uploading p_astro.json file to graceDB
• GWcelery is correctly ingesting PyCBC p_astro.json and do not use the internal p_astro calculation

Related issue: lscsoft/p-astro#12 (closed)

It will be solved by !1044 (closed) -> replaced by !1050 (closed) -> replaced by !1052 (merged)