chore: nuke protobuf fully

[tiina303]

Problem

This is live for a while on cloud and since 1.36.0 for self-hosted (63c783f).

Changes

Note that I nuked the code for 0004 async migration (other than the requirements and precheck part (which helps fail the upgrade if someone is trying to upgrade past it)). I believe rather than wasting time adopting the code that will be never ran (because the idea of async migrations was that we also update the code so that new installs wouldn't need to run them). Hence it would be a waste of everyone's time and resources to keep fixing the code and tests.

👉 Stay up-to-date with PostHog coding conventions for a smoother review.

How did you test this code?

Ran PostHog locally seemed to work fine and saw events coming in.

[macobo]

This does not do what it says it does:

• posthog/idl folder still exists
• plugin-server/src/config/idl still exists
• requirements-dev.in still has types-protobuf
• requirements.in still has protobuf
• plugin-server package.json still has protobuf dependencies

Schema snapshots are also unupdated?

[tiina303]

This does not do what it says it does:

Any preference between adding that to this pr vs updating the title to "... part 1" & following up

Schema snapshots are also unupdated?

Shouldn't there be a failing test?

[macobo]

Any preference between adding that to this pr vs updating the title to "... part 1" & following up

Ask for forgiveness, not permission.

Shouldn't there be a failing test?

Up to you to check - in general schema changes like this should probably result in a snapshot changing. You can verify this locally - maybe this one doesn't?

[macobo]

Rebase to fix the plugin server test fail