Deleting a migrated space may not delete all team calendars associated with that space

Issue Summary

This is reproducible on Data Center: no

Steps to Reproduce

1. Create team calendars on a cloud site or migrate a space containing team calendars
2. Hard delete the space 
3. Check database to see if subcalendar entries still exist 

Expected Results

Subcalendars associated with the space should be deleted

Actual Results

Some subcalendars from the space still exist in the database, which causes issues when trying to re-migrate that space. 

An error like these may appear when trying to remigrate a space into Cloud:

error Step failed, message: Import to cloud failed. Message: ERROR: duplicate key value violates unique constraint "AO_950DC3_TC_SUBCALS_pkey"; 

error Step failed, message: Import to cloud failed. Message: ERROR: duplicate key value violates unique constraint "AO_950DC3_TC_REMINDER_SETTINGS_pkey"; 

error Step failed, message: Import to cloud failed. Message: ERROR: duplicate key value violates unique constraint "AO_950DC3_TC_CUSTOM_EV_TYPES_pkey"; 

Additional notes

This doesn't impact if the space deletion is performed from UI
 

Workaround

Contact Atlassian support to help remove the orphan Calendar data.