Verify execution order using start time only
Verify execution order using start time only

After getting all that complicated stuff about writing to files and
reading from logs (or not - thanks init containers), I realized that
each TaskRun has a `startTime` and I can just check that to verify the
order 😅 and bonus, this sets us up nicely for adding a `runAfter`
instead of input output linking here.

tektoncd/pipeline,tektoncd/pipeline