[MSD benchmark] Fixes that workflow reminders of cancelled and rescheduled bookings are still sent

[khaliqgant]

MSD benchmark PR recreated from Martian Code Review Bench.

Source PR: calcom#7232
Dataset: cal_dot_com
Original title: Fixes that workflow reminders of cancelled and rescheduled bookings are still sent

What does this PR do?

Fixes that workflow emails are still sent for cancelled and rescheduled bookings. The fix of PR calcom#6991 was wrong and didn't work as expected.

The SendGrid endpoint DELETE /v3/user/scheduled_sends/${referenceId} was not used correctly. This endpoint deletes a cancelled scheduled email from scheduled_sends by removing the 'cancel' status (so email will again be scheduled).

The reason why cancelling our scheduled emails stopped working is that all cancerlled emails are saved in scheduled_sends until the scheduled date but the max. of pending cancellations is 100. Once we reached 100 pending cancellations, new cancellations failed and emails were still sent out.

The solution implemented in this PR:

• A new field cancelled is added to the workflowReminder model
• Once an already scheduled email is cancelled, the field is set to true (nothing else is done at this point in time)
• The CRON job scheduleEmailReminders is responsible for the final cancellation of the scheduled email (runs every 15 mins)
  • cancels all scheduled emails that are cancelled and that have their scheduled date within the next hour

Fixes calcom#7225

Environment: Staging(main branch) / Production

Type of change

• Bug fix (non-breaking change which fixes an issue)
• Chore (refactoring code, technical debt, workflow improvements)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update