Remove DataModuleConfig for the reduced config structure

[wonjuleee]

Summary

How to test

Checklist

• I have added unit tests to cover my changes.​
• I have added integration tests to cover my changes.​
• I have ran e2e tests and there is no issues.
• I have added the description of my changes into CHANGELOG in my target branch (e.g., CHANGELOG in develop).​
• I have updated the documentation in my target branch accordingly (e.g., documentation in develop).
• I have linked related issues.

License

• I submit my code changes under the same Apache License that covers the project.
  Feel free to contact the maintainers if that's a concern.
• I have updated the license header for each file (see an example below).

# Copyright (C) 2024 Intel Corporation
# SPDX-License-Identifier: Apache-2.0

[harimkang]

Overall, it looks good.
But I see that otx.core.config.data hasn't been cleared yet, will you be removing these in the next PR (DataModuleConfig, SubsetConfig, etc...)?

Also, due to the size of this PR, I think the integration test results should be shared.

[eunwoosh]

LGTM. Thanks for your huge effort :) Could you update integration test result?

[sungchul2]

LGTM. Let's check integation test results.

[wonjuleee]

Here is the integration test results. This PR passed 339 tests, while this has 8 failures on yolox explanations. But this is known issue in the develop.