Report count and name of tasks revived by parent
Report count and name of tasks revived by parent

Summary:
Tasks that need to be restarted are a signal of task loss, which is a Bad Thing.
This adds tracking of what kind of tasks were restarted, and how many.
Probably isn't useful for alerting; mostly for understanding our running system.

Test Plan: Existing tests

Reviewers: anupc

Reviewed By: anupc

Subscribers: changesbot

Differential Revision: https://tails.corp.dropbox.com/D215421

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