[CT] Increase number of allowable open files on CT masters
[CT] Increase number of allowable open files on CT masters

Bug: skia:9425
Change-Id: I1bea433eb1cbf76af29086c161db3e627fcd3823
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/242597
Reviewed-by: Ben Wagner aka dogben <3ef7217be91069877d94f7907ce5479000772cd3@google.com>
Commit-Queue: Ravi Mistry <9fa2e7438b8cb730f96b74865492597170561628@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot