Update default campaign automatically (#5082)

[gabina]

What this PR does

This PR schedules an automatic job that runs at the beginning of the spring and fall in northern hemisphere (please double-check these dates):

• March, 21st
• September, 21st

The job performs a default campaign update using DefaultCampaignUpdate class. First of all, it determines the current term (for example, 'spring_2024' or 'fall_2024'). If the current term already exists as a campaign (this is manually created each year according to the issue description), then the current term is set as the default campaign.
Otherwise, default campaign is not updated.

Notice that the update is only done when wiki_education feature is set to true, as I understand the scope of the issue is for Wiki Education Dashboard.

Closes #5082

Open questions and concerns

• Double-check the spring and fall start dates.
• Determine if there is any fallback that we want to use when the current term doesn't exist as a campaign.

[gabina]

Failing specs are not related to these changes.

[ragesoss]

Code and tests look great! I'll give it a spin soon.

[gabina]

I just fixed this, since the description was incorrectly saying "run default campaign update", when what I wanted to specified was the opposite.

[ragesoss]

We don't actually want to switch these based on the current season, but rather based on the academic calendar where 'spring' is the semester that starts in January. I think the right dates for this feature are January 1 through June 30 for spring, and July 1 through December 31 for fall.

[gabina]

We don't actually want to switch these based on the current season, but rather based on the academic calendar where 'spring' is the semester that starts in January. I think the right dates for this feature are January 1 through June 30 for spring, and July 1 through December 31 for fall.

oh that makes sense! I changed the dates on commit 927f807, and added some comments to clarify that dates are related to spring/fall semesters based on academic calendar.

[gabina]

I closed this PR by mistake and I don't think I'm able to reopen it now. But it should be re-opened, as it's ready for review and merge.