[pinpoint] Increase max attempt count from 40 to 50.
[pinpoint] Increase max attempt count from 40 to 50.

Spotted a job that would've found the culprit with a higher repeat count.
https://pinpoint-dot-chromeperf.appspot.com/job/17e1b884840000

Change-Id: Iaa2a0bcaeb29827750a7fcbd22661f6a22960fc6
Reviewed-on: https://chromium-review.googlesource.com/887960
Reviewed-by: Juan Antonio Navarro Pérez <1649bb5e6b9eafe026580e338065dc64ba6b80b2@chromium.org>
Commit-Queue: David Tu <baa605d781958521249fdcf7bad76b01d943134a@chromium.org>

catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult