Run posthog-production CI in a way testing migration continuity

[Twixes]

Changes

This changes the posthog-production GitHub Actions test on this repo to check if migrating from current master to the PR is possible. I caught this issue of migrations working just fine from scratch but not from master a couple of times before merging in the past, but this should 100% ensure that such a bug will never slip through.

[macobo]

Q: Could it be worth it to make this into a separate pipeline/check?

Rolling it into Backend CI tests would make that check slower and harder to figure out what broke - i.e. was it the tests or the migrations?

[paolodamico]

My feedback:

• From L236 shouldn't we also run tests for EE? We fully use EE features on PostHog Cloud.
• Perhaps take the opportunity to change all references (e.g. L141/L142) from multi tenancy to cloud?
• From the code it was a bit unclear the purpose of checking out master first and then current, maybe add some comment lines?

[Twixes]

Addressing @paolodamico:

1. What part of the test workflow do you mean by also running tests for EE?
2. Yep, can rename to Cloud, though the repo is still called posthog-production and the main app in there is multi_tenancy, hm…
3. Will add comments.

[paolodamico]

Great! So just re 1, what I meant is that on these multitenancy tests we're only testing posthog, multi_tenancy & messaging apps (i.e. skipping ee) [see line 236]. My feedback was that maybe we should include CH on multitenancy tests and test ee app too (as since /~https://github.com/PostHog/posthog-production/pull/40, posthog-production tests rely on CH), but #2062 already introduced this since the last review.

[Twixes]

@paolodamico Not sure if this now runs EE tests the way you meant? Do say if there's an enhancement to be made still.
@macobo I'd be against having a whole separate check for such a specific thing, I think it fits in quite well with Cloud tests.

[paolodamico]

small change to make sure EE tests are run in posthog-production context too but looks pretty good!