fix(alluxio): should use json tag instead of yaml tag

[weixiao-huang]

Ⅰ. Describe what this PR does

Use json tag instaed of yaml tag since we use k8s yaml to unmarshal, which only use json tag

Ⅱ. Does this pull request fix one issue?

fixes #2772

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

Ⅳ. Describe how to verify it

See the related issue

Ⅴ. Special notes for reviews

[fluid-e2e-bot]

Hi @weixiao-huang. 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.

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[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[cheyang]

/lgtm
/approve

[fluid-e2e-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cheyang

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[cheyang]

Thanks @weixiao-huang

[codecov]

Codecov Report

Merging #2773 (dcaf9bc) into master (bcf844b) will not change coverage.
The diff coverage is n/a.

❗ Current head dcaf9bc differs from pull request most recent head 0db9a49. Consider uploading reports for the commit 0db9a49 to get more accurate results

@@           Coverage Diff           @@
##           master    #2773   +/-   ##
=======================================
  Coverage   66.91%   66.91%           
=======================================
  Files         383      383           
  Lines       22289    22289           
=======================================
  Hits        14914    14914           
  Misses       5627     5627           
  Partials     1748     1748           

Impacted Files	Coverage Δ
pkg/ddc/alluxio/types_selector.go	90.00% <ø> (ø)

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[TrafalgarZZZ]

/lgtm