composer operations need to set job load from profile load when creating jobs

Steps to reproduce:

1. Set a jobload in an encoding profile as documented at https://docs.opencast.org/r/3.x/admin/configuration/load/#step-3-setting-the-load-values-for-encoding-profiles for example:

profile.presenter-mp4-parallel.http.jobload = 3.0

2. Create a workflow that uses the composer operation with the profile

Actual Results:

The job load for the operation is the default 1.0 rather than the jobload specified in the profile

Expected Results:

The operation's job load should be set from the profile's job load.