fix(tidb-engine-ext): link git and registry cargo cache

[purelind]

Directly setting the CARGO_HOME variable will result in losing the default config and env configurations，so just creat link for git and registry of cargo cache.

[ti-chi-bot]

I have already done a preliminary review for you, and I hope to help you do a better job.

Based on the PR title and description, it seems that the changes are related to fixing an issue with the tidb-engine-ext repository where setting the CARGO_HOME variable results in losing the default configuration and environment configurations. To fix this issue, the changes proposed in this PR are to create a link for the git and registry of cargo cache instead of directly setting the CARGO_HOME variable.

Looking at the diff, the changes seem to be straightforward. The script now removes the .git and registry directories from the cargo cache and then creates symbolic links for the git and registry directories in the cargo cache.

However, the PR does not mention why the CARGO_HOME variable was set in the first place and whether there are any other potential issues with removing it and using symbolic links instead.

It would be good to clarify these points in the PR description or in the comments. Additionally, it may be worth considering if there are any security implications to creating symbolic links in the cargo cache.

Overall, the changes proposed in this PR seem reasonable. It would be good to add some additional context around the reasoning behind the changes and any potential issues to be aware of.

[ti-chi-bot]

I have already done a preliminary review for you, and I hope to help you do a better job.

Based on the pull request description and code diff, it appears that the following changes were made:

• Instead of directly setting the CARGO_HOME environment variable, the pull request creates a symlink for the git and registry directories of the Cargo cache.
• The CARGO_HOME environment variable is no longer set.
• The CPU limit for the container has been increased to 12.
• The CARGO_NET_GIT_FETCH_WITH_CLI environment variable is still set to "true".
• The cargo-cache volume is still mounted at /cargo-cache.

Potential problems:

• The code diff does not have a test case to validate the changes.
• The pull request does not give a clear explanation of why the change is made.
• The pull request does not explain how the suggested fix is expected to improve the current situation.

Fixing suggestions:

• Add test cases to validate the changes made in the pull request.
• Add a detailed explanation of why the change is made to the pull request description.
• Add an explanation of how the suggested fix is expected to improve the current situation to the pull request description.

[CalvinNeo]

lgtm

[ti-chi-bot]

@CalvinNeo: adding LGTM is restricted to approvers and reviewers in OWNERS files.

In response to this:

lgtm

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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