Summary:
For half of the crash_test run, disable fail point for file appending, in order to trigger other fail point more frequently.
Also, tune crash test parameter a little bit for it to initialize faster.
Test Plan: Run crash_test and make sure it issues db_stress commands as expected.
Reviewers: yhchiang, igor, rven, anthony, IslamAbdelRahman, kradhakrishnan
Reviewed By: kradhakrishnan
Subscribers: leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D48843