Add a cron flaky check golang CI job

[Jorropo]

It would be nice if at a regular interval (let's say every monday at 3 UTC) a CI job would run with -count=25 or something else dumb like this. And report any new flaky failure. It would force us to not have any flake test.

[Jorropo]

An alternative could be something like golang's watchflake, where a bot would notice runs that failed were restarted and then sucesfully completed, and open an issues for theses. We could also use monkeybrains to do that, forcing us to report any flake that happened if we reran a test.