fix(google-health): keep the hourly sync inside its job's expiry

An account whose backfill slice held it made the hourly job wait up to
eight minutes, and the sync after the wait ran as long as it needed:
past the fifteen-minute expiry pg-boss failed the job and retried it
beside the run still going. The pass now spends the job's budget: the
lock wait is capped at what is left, the sync's walks stop when the
budget is spent and leave the rest of the window to the next hour (the
cycle is not stamped), and an account reached after that is skipped.
A stop on the budget is not counted as a failure to retry.

docs/integrations/google-health.md

@@ -157,7 +157,10 @@ still a failure.
 
 The hourly sync waits for the slice that is running (up to eight minutes)
 instead of skipping the account, so recent data keeps arriving while an old
-history is still coming in.
+history is still coming in. The hourly job stays inside its own fifteen-minute
+limit: the wait is cut short when the job's time runs low, the sync after it
+gets only what is left and leaves the rest of its window to the next hour, and
+an account the job reaches after its time is up waits for the next hour.
 
 Google limits how many requests one account may make per minute. When a sync
 reaches that limit Google answers `429`, and HealthLog waits and repeats the