Enable Go modules and remove GOPATH requirement from docs

[jakharmonika364]

Ⅰ. Describe what this PR does

Enables Go modules in the Makefile and updates the developer documentation to remove GOPATH-based setup instructions.

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Ⅱ. Does this pull request fix one issue?

fixes #5669

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Ⅲ. List the added test cases (unit test/integration test) if any, please explain if no tests are needed.

No new tests needed - this is a build configuration and documentation update. Verified that make fmt runs successfully with the new GO_MODULE=on setting.

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Ⅳ. Describe how to verify it

1. Clone the repo without setting up GOPATH
2. Run make fmt - should work without errors
3. Follow the updated setup instructions in docs/en/dev/how_to_develop.md

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Ⅴ. Special notes for reviews

The Makefile change from GO_MODULE ?= off to GO_MODULE ?= on aligns with the existing go.mod file and modern Go development practices. Documentation changes remove confusing GOPATH setup steps that were causing issues for new contributors.

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request modernizes the project's build configuration and developer onboarding experience by fully embracing Go modules. It activates Go modules in the build system and removes all references to GOPATH-dependent setup steps from the documentation, making the development environment easier to set up and maintain.

Highlights

• Go Modules Activation: The Makefile has been updated to explicitly enable Go modules by setting GO_MODULE ?= on, aligning the project with modern Go development practices.
• Documentation Streamlining: Developer documentation (both English and Chinese versions) has been revised to remove outdated GOPATH-based setup instructions, simplifying the onboarding process for new contributors.

Changelog

• Makefile
  • Set GO_MODULE variable to 'on'.
• docs/en/dev/how_to_develop.md
  • Removed 'export GOPATH' and 'mkdir $GOPATH' commands from source code acquisition instructions.
  • Updated the note to state that Fluid uses Go modules and no GOPATH setup is required.
  • Modified the 'ln -s' command for charts to use '$(pwd)' instead of '$GOPATH'.
• docs/zh/dev/how_to_develop.md
  • Removed 'export GOPATH' and 'mkdir $GOPATH' commands from source code acquisition instructions.
  • Updated the note to state that Fluid uses Go modules and no GOPATH setup is required.
  • Updated the 'controller-gen' installation note to reference '$(go env GOPATH)/bin' instead of '$GOPATH/bin'.
  • Modified the 'ln -s' command for charts to use '$(pwd)' instead of '$GOPATH'.

Activity

• The pull request was created by jakharmonika364 to enable Go modules and update documentation.
• No further review comments or activity have been recorded yet.

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[fluid-e2e-bot]

Hi @jakharmonika364. Thanks for your PR.

I'm waiting for a fluid-cloudnative member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Details

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[gemini-code-assist]

Code Review

This pull request correctly enables Go modules by default in the Makefile and updates the developer documentation to reflect this change. The removal of GOPATH-based setup instructions in both English and Chinese documentation simplifies the development environment for new contributors. The changes are clear and align with modern Go development practices. I've found one minor issue in the Chinese documentation that needs to be addressed.

_{Note: Security Review did not run due to the size of the PR.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 61.04%. Comparing base (21c5683) to head (8ff8b22).
⚠️ Report is 7 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #5677   +/-   ##
=======================================
  Coverage   61.04%   61.04%           
=======================================
  Files         444      444           
  Lines       30540    30540           
=======================================
  Hits        18643    18643           
  Misses      10360    10360           
  Partials     1537     1537           

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[TrafalgarZZZ]

/lgtm

[cheyang]

/lgtm
/approve

[fluid-e2e-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cheyang

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• OWNERS [cheyang]

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