After https://github.com/ray-project/ray/pull/24066, some release tests are running into:
```
ModuleNotFoundError: No module named 'ray.train.impl'
```
This PR simply adds a `__init__.py` file to resolve this.
We also add a 5 wecond delay for client runners in release test to give clusters a bit of slack to come up (and avoid ray client connection errors)
What: Quotes pip install packages in local environment setup for client runner.
Why: Strings like pyarrow>=6.0.1<7.0.0 currently don't work as they are interpreted as output redirection.
Apparently, ray gets imported somewhere before running the client runner (maybe from an anyscale package). This means that we need to reload the ray package after installing a matching local ray wheel.
Additionally, job submission should also install a matching local ray to match with the job submission server.
This PR supports the job-based file manager and runner. It will be the backbone of k8s migration.
The PR handles edge cases that originally existed in the old e2e.py job-based runners.
Adds a unit-tested and restructured ray_release package for running release tests.
Relevant changes in behavior:
Per default, Buildkite will wait for the wheels of the current commit to be available. Alternatively, users can a) specify a different commit hash, b) a wheels URL (which we will also wait for to be available) or c) specify a branch (or user/branch combination), in which case the latest available wheels will be used (e.g. if master is passed, behavior matches old default behavior).
The main subpackages are:
Cluster manager: Creates cluster envs/computes, starts cluster, terminates cluster
Command runner: Runs commands, e.g. as client command or sdk command
File manager: Uploads/downloads files to/from session
Reporter: Reports results (e.g. to database)
Much of the code base is unit tested, but there are probably some pieces missing.
Example build (waited for wheels to be built): https://buildkite.com/ray-project/kf-dev/builds/51#_
Wheel build: https://buildkite.com/ray-project/ray-builders-branch/builds/6023
