Design doc: https://docs.google.com/document/d/1yLZhxvwQw60Tiox2LZkIdQ4ZhBF7DuzoJbCFci-dG0U/edit?ts=5c13ff04

There are three steps to reducing CQ-level build retries:

1) Measure the utility of CQ-level build retries: https://crbug.com/903495
2) Increase the utility of CQ-level build retries: 
  2a) Find and fix occurrences of INVALID_TEST_RESULTS: https://crbug.com/881991
  2b) Find and fix other causes of false rejects. e.g. https://crbug.com/889181, https://crbug.com/888734, etc.
3) Implement mechanism to selectively turn off CQ-level build retries:  https://crbug.com/910193 . Begin reducing CQ-level build retries while keeping a close eye on (1).