This change corrects the case where an ASAP job is scheduled to start at a later date/time because its score is not yet positive.
With this change, only executeJob does switch the job state to JOB_BUSY, so that no other part of the code can unexpectedly start the job.
Note that periodic score update is prepared in this commit to display negative scores properly, but score computation needs rework beforehand.
But this does not solve the problem of duplicated repeated jobs where only the pipeline tracking activity is enabled, which has similar symptom.
A new test vector, 'distant_jobs_no_twilight', has two north-hemisphere targets with opposite transit times.
This allows testing a job immediately, and having the scheduler sleeping to wait for the next.