Change how the JSON is updated for readability

A massive one-liner to add a bunch more variables to the JSON
datafile isn't fun any more. Shift to using a heredoc which should
make the options we are setting more readable, as well as easier to
change in future.

Change-Id: I3cf779326d682f0afe5f5399e37a8b34e62ac54c
Merge "Change how the JSON is updated for readability"