Calendar should not be removed from run-time when updating the timeslot period

Current Situation

• If a calendar is assigned a job's run-time with the period "timeslot" and is stored with the database then when using the "Edit run-time" operation once again for this job the calendar assignment is lost.

How to Reproduce

• Create a Calendar using JOC Cockpit.
• Create a job, assign the Calendar the job's run-time and define a timeslot period.
• Deploy the job.
• Open the run-time editor in the configuration view again
• update the timeslot from the run-time period of the job.
• Deploy the job.
• Switch to the jobs view and navigate to the job
• Review the run-time to observe that the calendar assignment has been removed.

Desired Behavior

• The Calendar assignment should not be removed from the run-time when updating a timeslot period.