This change uses the new os-refresh-config --timeout argument to set a
kill timeout for stalled os-refresh-config runs.
4 hours is a reasonable conservative value since it matches the stack
timeout - but it can be set shorter in the future based on actual run
times.
Change-Id: I433f558515df24736263ec0d50de08ad8f78498f
Closes-Bug: #1595722
DependsOn: Ibcbb2090aed126abec8dac49efa53ecbdb2b9b2c