What does this PR do?

Race condition: schedule documents were deleted immediately after spawning coroutines, before jobs were queued. Container shutdown between coroutine spawn and trigger execution caused permanent job loss.

Changes:

• Move schedule deletion inside coroutine, after trigger() call
• Move unset() operation into coroutine to maintain consistency
• Add $dbForPlatform to coroutine closure

Before:

\go(function () use (...) {
    Co::sleep($delay);
    $queueForFunctions->trigger();
});

$dbForPlatform->deleteDocument('schedules', $schedule['$id']);  // ← Deleted before trigger completes

After:

\go(function () use (..., $dbForPlatform) {
    Co::sleep($delay);
    $queueForFunctions->trigger();
    $dbForPlatform->deleteDocument('schedules', $schedule['$id']);  // ← Deleted after trigger completes
    unset($this->schedules[$schedule['$sequence']]);
});

Pattern now matches ScheduleMessages.php implementation for one-time scheduled tasks.

Test Plan

Existing e2e test testCreateScheduledAtExecution in FunctionsScheduleTest.php validates scheduled execution behavior. The fix ensures jobs survive container restarts between enqueue scheduling and execution.

Related PRs and Issues

• Addresses delayed execution reliability during container lifecycle events

Checklist

• Have you read the Contributing Guidelines on issues?
• If the PR includes a change to an API's metadata (desc, label, params, etc.), does it also include updated API specs and example docs?

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