Switch cron jobs from pubsub to HTTP triggers

[brian-lou]

This PR deprecates pubsub endpoints and switches to HTTP endpoints for triggering cron jobs. This is the first step of the migration. Once this has been merged & is stable, the cron jobs will be redirected away from pubsub. Once this is stable, we will remove the old pubsub endpoints in another PR.

[IanWoodard]

Let's leave the old way in until the other change is merged so there is no downtime for these cron jobs

[codecov]

Codecov Report

Attention: Patch coverage is 96.88196% with 14 lines in your changes missing coverage. Please review.

Project coverage is 90.27%. Comparing base (2e20019) to head (3c471d5).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/jobs/slackNotifications.ts	94.11%	4 Missing and 5 partials ⚠️
src/jobs/index.ts	92.30%	4 Missing ⚠️
src/jobs/stalebot.ts	98.41%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #872      +/-   ##
==========================================
+ Coverage   89.46%   90.27%   +0.80%     
==========================================
  Files         126      131       +5     
  Lines        3693     4142     +449     
  Branches      744      881     +137     
==========================================
+ Hits         3304     3739     +435     
+ Misses        377      366      -11     
- Partials       12       37      +25     

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