Fix flaky test in issue#3096

[Mukta13]

What this PR does / why we need it?

The fix for: #3096

Summary of your change

This change introduces a helper method, assertMapsEqual(), that reduces test flakiness by serializing two objects to JSON, converting them into maps, and comparing their content. It ensures stable data comparison by avoiding issues with non-deterministic behavior or inconsistent serialization. Error handling is added to manage potential serialization failures.

Can be tested by running:

mvn -pl core edu.illinois:nondex-maven-plugin:2.1.7:nondex -Dtest=com.alibaba.fastjson2.codec.JSONBTableTest3#test_0


mvn -pl core edu.illinois:nondex-maven-plugin:2.1.7:nondex -Dtest=com.alibaba.fastjson2.codec.JSONBTableTest3#test_1

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.

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[Mukta13]

Hi. Can this PR be reviewed as well? Thanks!! @wenshao