Fix non-determinsm for Issue#3126

[Mukta13]

What this PR does / why we need it?

This is for issue#3126 This PR addresses three non-deterministic tests found in the following files, which lead to non deterministic test results and inconsistent builds.

Summary of your change

• Modified Flaky Tests:

  • Issue3831.java:

  • Updated test_for_issue3831() to ensure consistent ordering of properties in the expected output.

  • Issue2644.java:

  • Adjusted testJsonBackReference() to fix the ordering of fields in the expected JSON output, ensuring that the test matches the actual output format.

  • Issue2836.java:

  • Revised test() to standardize the structure of the expected output, aligning it with the actual output to eliminate discrepancies.

Can be tested using:

mvn -pl core edu.illinois:nondex-maven-plugin:2.1.7:nondex -Dtest=com.alibaba.fastjson2.v1issues.issue_3800.Issue3831#test_for_issue3831

mvn -pl core edu.illinois:nondex-maven-plugin:2.1.7:nondex -Dtest=com.alibaba.fastjson2.issues_2600.Issue2644#testJsonBackReference

mvn -pl core edu.illinois:nondex-maven-plugin:2.1.7:nondex -Dtest=com.alibaba.fastjson2.issues_2800.Issue2836#test

Please indicate you've done the following:

• [Yes ] Made sure tests are passing and test coverage is added if needed.
• [ Yes] Made sure commit message follow the rule of Conventional Commits specification.
• [Yes ] Considered the docs impact and opened a new docs issue or PR with docs changes if needed.