Improve self-hosted Sentry initialization to run <5 minutes in VM's/CI

[hubertdeng123]

As of right now, self-hosted Sentry takes way too long to start up. The majority of this time is spent running the ./install.sh script. It's a priority for us to ensure that our own devs have a pleasant experience working with self-hosted. As Sentry has grown, more and more features have added that slow down the initialization process. This will only get worse as time goes on and more code is added, and we should provide a way for our devs to spin up a minimal self-hosted instance for their needs.

Initialization of self-hosted Sentry takes ~11 minutes.

Integration tests take >30 minutes to finish.

Benefits:

1. Devs will have a much easier time working in self-hosted, right now it takes ~20-30 min to setup self-hosted from scratch and get it up and running. CI is taking 11 minutes to setup self-hosted, which happens multiple times during integration tests.
2. CI workflows will take far less time to complete, unblocking dev processes in other repos. It will also make it easier to implement self-hosted at some part of the deployment pipeline, forcing devs to keep self-hosted in mind.
3. We will have a much easier time debugging self-hosted issues 😁

### Tasks
- [ ] Preserve docker volumes in an empty state of self-hosted so they won't need to be built every time
- [ ] instead of running through a one step install script, have a docker-compose.yml file that is specific to certain platforms