Add more debugging to the DigestTest

This test sometimes fails, but we don't know what the coefficient of
variation is on the test results. Add this to the debug output so we can
see if there is just some wild swing during testing.

Also add a few rounds of warm-up as well.

Bug: 24011092
Change-Id: Ic58f106f68eb93976e3f030e2f23e0156fe84be8
(cherry picked from commit 5fe1cd001f38fba460ac0ce5c15b85250e400f25)
2 files changed