Trigger master-branch optprof runs periodically

[rainersigwald]

Today, optprof collection from (internal-only link) https://dev.azure.com/devdiv/DevDiv/_release?definitionId=1370&view=mine&_a=releases runs for every vs* build but not for master builds. We should run it on some schedule--not every build. Maybe weekly?

[Forgind]

Now set to run every week on Fridays at 3pm PST.