Reduce the number of iterations in PreEnrollTest am: 744b028807 am: f80eb3cb9e am: 8611b593d0

Original change: https://googleplex-android-review.googlesource.com/c/platform/hardware/interfaces/+/11712201

Change-Id: I875a0b5a1f67e470e2e695b8eea18c42332485ba