Instead of trying to make one step take one sequence of frames,
one run step per frame always. This will scale better for traces
that are very long and cannot complete in the short times we use
on the bots.

Adds an explicit step round-up feature so that we can always run
chunks of full trace sequences when we are not running with a
fixed maximum number of steps.

Bug: b/172977194
Change-Id: I0f069a66a86d8c4a698ebffb66782d13843539a5
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2545884Reviewed-by: Cody Northrop <cnorthrop@google.com>
Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>