is it possible to trim the table output for a specific job?
Yes.

The CommandLog cleanup is from Ola Hallengren's Maintenance Solution, so doesn't affect msdb history directly.

Use sp_purge_jobhistory, like so:

sp_purge_jobhistory   
   {   [ @job_name = ] 'job_name' |   
     | [ @job_id = ] job_id }  
   [ , [ @oldest_date = ] oldest_date ]  


Per the documentation, 'job_name' is the name of the job for which to delete the history records. Either job_id or job_name must be specified, but both cannot be specified.