Start master feature test jobs 4 hours earlier

Start master feature test jobs 4 hours earlier

Start the airship master feature tests jobs 4 hours earlier. Jobs
sometimes fail overnight due to webhook failures, which seem related to
high I/O latency in the environment. We're guessing that the high I/O
latency may be caused by CityCloud's disaster recovery snapshots and
hope to avoid the period of their higher latency by starting the jobs
earlier in the evening.

Change-Id: I9e41e862d88742060f13cea6e83eb90ca368c1ea