Sqlserver : Make job_name param on start jobs task required

Currently the start_sql_agent_job.json specifies the job_name parameter as optional. This should be a required parameter. In the powershell code that runs the job the parameter is already required. This will cause the task to hang if it is called without passing this parameter.

This ticket should also remove a conditional check to see if the job_name parameter has been passed, as for this particular task the job_name will always be passed into the script, and the else block contains logic that would be a problem if it ever ran.