add cronjob that clears old tasks every midnight

[aronasorman]

Summary

Description of the change(s) you made

Create a cronjob that spawns a pod that clears tasks older than 7 days.

Manual verification steps performed

1. Create cronjob on my local machine that connects to develop
2. Run that cronjob manually
3. Check that there are no jobs older than 7 days

Reviewer's Checklist

This section is for reviewers to fill out.

• Automated test coverage is satisfactory
• PR is fully functional
• PR has been tested for accessibility regressions
• External dependency files were updated if necessary (yarn and pip)
• Documentation is updated
• Contributor is in AUTHORS.md

[codecov]

Codecov Report

Merging #3066 (6f66823) into unstable (9264221) will decrease coverage by 0.18%.
The diff coverage is n/a.

❗ Current head 6f66823 differs from pull request most recent head 7acb364. Consider uploading reports for the commit 7acb364 to get more accurate results

@@ Coverage Diff @@## unstable #3066 +/- ##
============================================
- Coverage 86.12% 85.93% -0.19% 
============================================
Files 305 304 -1 Lines 16459 16403 -56 ============================================
- Hits 14175 14096 -79 - Misses 2284 2307 +23 

Impacted Files	Coverage Δ
...tentcuration/contentcuration/utils/celery/tasks.py	76.27% <0.00%> (-5.99%)	⬇️
contentcuration/contentcuration/tasks.py	57.62% <0.00%> (-3.96%)	⬇️
contentcuration/contentcuration/tasks_test.py	83.33% <0.00%> (-2.04%)	⬇️
contentcuration/contentcuration/models.py	84.58% <0.00%> (-1.98%)	⬇️
...ion/contentcuration/tests/viewsets/test_channel.py	92.91% <0.00%> (-1.27%)	⬇️
...ntcuration/contentcuration/tests/test_asynctask.py	91.42% <0.00%> (-1.08%)	⬇️
contentcuration/contentcuration/views/base.py	62.82% <0.00%> (-0.62%)	⬇️
...ontentcuration/contentcuration/viewsets/channel.py	79.74% <0.00%> (-0.43%)	⬇️
contentcuration/contentcuration/views/internal.py	85.37% <0.00%> (-0.23%)	⬇️
...contentcuration/tests/views/test_views_internal.py	97.24% <0.00%> (-0.21%)	⬇️
... and 12 more

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[aronasorman]

The kubernetes part looks good to me!

[bjester]

This appears to introduce a regression. After publishing, the PUBLISH button is enabled.

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities
0 Security Hotspots
1 Code Smell

No Coverage information
No Duplication information

[bjester]

Publishing issue appears resolved by #3256