[autotest] Reduce flakiness of common_util_test:testRunCommandRetrySleep

This test is known to be flaky because it relies on sleep(). It
records the time spent on RunCommand retries and checks it
against the epxected time.

This CL tries to reduce flakiness by increase the tolerated time
mismatch. If we still see it flakes, we should consider to eleminate this

TEST=run this test.

Change-Id: I5d712d0aea1bc6cfcd009a584e6963aa9272d83e
Previous-Reviewed-on: https://chromium-review.googlesource.com/175960
(cherry picked from commit b79fad5b90cb9a64d4cc59310e4bafc50c2d90d7)
Reviewed-on: https://chromium-review.googlesource.com/177644
Reviewed-by: Prashanth B <beeps@chromium.org>
Commit-Queue: Fang Deng <fdeng@chromium.org>
Tested-by: Fang Deng <fdeng@chromium.org>
1 file changed