Werk #11951: mssql_jobs: fix Check_MK and Check_MK_Discovery crash

The Check_MK and Check_MK Discovery services crashed in association with the mssql_jobs check with the following error message:

ValueError (time data ' 000000' does not match format '%Y%m%d %H%M%S')

This crash occurs when the next run date and next run time of the MSSQL jobs are not set (i.e. set to NULL). This has been fixed.

To the list of all Werks