Revert "[9.3 release] Copy Gemfile from 9.2 branch and update only LS core version."

[mashhurs]

Reverts #18504

[github-actions]

🤖 GitHub comments

Just comment with:

• run docs-build : Re-trigger the docs validation. (use unformatted text in the comment!)
• /run exhaustive tests : Run the exhaustive tests Buildkite pipeline.

[mergify]

This pull request does not have a backport label. Could you fix it @mashhurs? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-8./d is the label to automatically backport to the 8./d branch. /d is the digit.
• If no backport is necessary, please add the backport-skip label

[donoghuc]

oops!

[elasticmachine]

💚 Build Succeeded

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• Commit: c22eb76