Previously the nightly release was scheduled only on Mondays, so a
failed run left users without nightly builds for a whole week.
Now the schedule triggers every weekday at 00:00 UTC, but the release
only proceeds when the latest published nightly release is older than
NIGHTLY_RELEASE_MAX_AGE_DAYS (5) days. The check runs in
allocate-runners before any EC2 runner is allocated, and gates all
schedule-driven jobs (including the Slack notification, so a skipped
nightly is silent). Tag pushes and manual dispatches are unaffected.
Signed-off-by: Ning Sun <sunning@greptime.com>
Ning Sun
a7f99b3425