Remove redundant pipebot.file config option.
Remove redundant pipebot.file config option.

The comment above it is incorrect - we've been using a submoduled
copy of pipebot for ages now, and that has its own config of where
the pipe is.

Change-Id: I38c1331976bf997720998b4eae1f1ce66afcedc5

jmorse/cyanide,jmorse/cyanide,jmorse/cyanide,jmorse/cyanide