[WIP] Add e2e test for tune api with LLM hyperparameter optimization

[helenxie-bit]

What this PR does / why we need it:
This PR adds an e2e test for the tune API, specifically for the scenario of importing external models and datasets for LLM hyperparameter optimization.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Checklist:

• Docs included if any changes are user facing

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[helenxie-bit]

/area gsoc

[helenxie-bit]

Ref: #2339

[helenxie-bit]

The e2e test for the tune API has been consistently failing due to a "Timeout Error," and I have been investigating the root cause. I set the retain_trials parameter to True and retrieved the logs from the pod in the Experiment. The logs revealed that both the pytorch container and the metrics-logger-and-collector container exited with an Error 137.

When I ran kubectl describe pod $POD_NAME -n default, I noticed the following events. One specific event, "SandboxChanged," stood out as potentially problematic:

Events:
  Type    Reason          Age                    From               Message
  ----    ------          ----                   ----               -------
  ...
  Normal  SandboxChanged  3m (x2 over 3m43s)     kubelet            Pod sandbox changed, it will be killed and re-created.
  ...

However, when I checked the pod logs using kubectl logs $POD_NAME -n default --all-containers, everything appeared normal, and the logs confirmed that "Training is complete."

I also examined the kubelet and container runtime logs. While the kubelet logs provided no additional insights, the container runtime logs displayed the following error, which I believe may be related to the issue:

Sep 24 20:39:17 fv-az1984-731 dockerd[3344]: time="2024-09-24T20:39:17.335535766Z" level=error msg="Can not stat \"/mnt/docker/overlay2/8b5c0a1c561c3db93ea374a55b4004ebffd509c370cd11140b1275bf004fc8cd/merged/run/mysqld/mysqlx.sock\": lstat /mnt/docker/overlay2/8b5c0a1c561c3db93ea374a55b4004ebffd509c370cd11140b1275bf004fc8cd/merged/run/mysqld/mysqlx.sock: no such file or directory"

@andreyvelich @tenzen-y Do you have any thoughts on how to resolve this issue?