minor cleanup in job-manager journal and job-list (mostly inline docs)

[garlick]

@chu11 and I were both looking through the job-list source to be sure all is OK before we tag, and we both spotted some incorrect source comments. Al, feel free to add to this PR.

[chu11]

LGTM, per offline discussion, my stuff will go into a different PR.

[garlick]

I added some more - maybe have one more look before I set MWP?

[chu11]

LGTM still

[garlick]

restarting fedora 38 builder that failed here:

2024-04-03T14:36:57.2543908Z not ok 7 - flux-cron tab works for month
2024-04-03T14:36:57.2544186Z 
2024-04-03T14:36:57.2544369Z expecting success: 
2024-04-03T14:36:57.2544670Z     $set_faketime Jun 5 15:45 2016 &&
2024-04-03T14:36:57.2545175Z     id=$(flux_cron at "Jun 6 15:45:00 2016" flux event pub t.cron.complete) &&
2024-04-03T14:36:57.2545723Z     test_when_finished "flux cron delete ${id}" &&
2024-04-03T14:36:57.2546217Z     next=$(date +%s --date="Jun 6 15:45 2016") &&
2024-04-03T14:36:57.2546629Z     cron_entry_check ${id} type datetime &&
2024-04-03T14:36:57.2547029Z     cron_entry_check ${id} stopped false &&
2024-04-03T14:36:57.2547473Z     cron_entry_check ${id} typedata.next_wakeup ${next} &&
2024-04-03T14:36:57.2547927Z     ${event_trace} t.cron t.cron.complete \
2024-04-03T14:36:57.2548318Z         $set_faketime Jun 6 15:45 2016 &&
2024-04-03T14:36:57.2548712Z     cron_entry_check ${id} stats.count 1 &&
2024-04-03T14:36:57.2549096Z     cron_entry_check ${id} stopped true
2024-04-03T14:36:57.2549364Z 
2024-04-03T14:36:57.2549684Z libfaketime: In parse_ft_string(), failed to parse FAKETIME timestamp.
2024-04-03T14:36:57.2550283Z Please check specification  with format %Y-%m-%d %T

[codecov]

Codecov Report

Merging #5850 (b47b3c9) into master (4598d41) will increase coverage by 0.03%.
Report is 6 commits behind head on master.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5850      +/-   ##
==========================================
+ Coverage   83.26%   83.30%   +0.03%     
==========================================
  Files         513      513              
  Lines       82727    82727              
==========================================
+ Hits        68882    68915      +33     
+ Misses      13845    13812      -33     

Files	Coverage Δ
src/modules/job-list/job_state.c	75.82% <ø> (ø)
src/modules/job-manager/journal.c	80.34% <ø> (ø)
src/modules/job-manager/prioritize.c	72.61% <ø> (ø)

... and 18 files with indirect coverage changes