optimize: support resolving JAVA_HOME from symbolic links when `which…

[llkkk]

… java` is used

Please do not create a Pull Request without creating an issue first.

What is the purpose of the change

This change optimizes the logic for detecting JAVA_HOME in the Nacos startup script. Specifically, it adds support for resolving JAVA_HOME from symbolic links when the which java command is used. This enhancement ensures compatibility with systems where JAVA_HOME is not explicitly set but java is available via a symbolic link.

Brief changelog

• Added a check to resolve symbolic links for JAVA_PATH when which java is used.
• Updated the logic to derive JAVA_HOME from the resolved JAVA_PATH.

Verifying this change

To verify this change:

1. Test the script on a system where JAVA_HOME is not set but java is available via a symbolic link (e.g., /usr/bin/java -> /usr/java/jdk1.8.0_361/bin/java).
2. Ensure that the script correctly detects and sets JAVA_HOME to /usr/java/jdk1.8.0_361.
3. Test the script on systems with and without symbolic links to confirm backward compatibility.

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• Make sure there is a Github issue filed for the change (usually before you start working on it). Trivial changes like typos do not require a Github issue. Your pull request should address just this issue, without pulling in other changes - one PR resolves one issue.
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[CLAassistant]

All committers have signed the CLA.

[github-actions]

Thanks for your this PR. 🙏
Please check again for your PR changes whether contains any usage/api/configuration change such as Add new API , Add new configuration, Change default value of configuration.
If so, please add or update documents(markdown type) in docs/next/ for repository nacos-group/nacos-group.github.io

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感谢您提交的PR。 🙏
请再次查看您的PR内容，确认是否包含任何使用方式/API/配置参数的变更，如：新增API、新增配置参数、修改默认配置等操作。
如果是，请确保在提交之前，在仓库nacos-group/nacos-group.github.io中的docs/next/目录下添加或更新文档（markdown格式）。

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.28%. Comparing base (762303b) to head (935a443).

Additional details and impacted files

@@              Coverage Diff              @@
##             develop   #12982      +/-   ##
=============================================
- Coverage      72.28%   72.28%   -0.01%     
  Complexity      9999     9999              
=============================================
  Files           1309     1309              
  Lines          41991    41991              
  Branches        4405     4405              
=============================================
- Hits           30353    30352       -1     
- Misses          9514     9516       +2     
+ Partials        2124     2123       -1     

see 1 file with indirect coverage changes

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[DarkAngel35-commits]

gh pr checkout 12982

[KomachiSion]

Please sign cla first

[wuyfee]

$\color{green}{SUCCESS}$
DETAILS
✅ - docker: success
✅ - deploy (standalone & cluster & standalone_auth): success
✅ - e2e-java-test (standalone & cluster & standalone_auth): success
✅ - e2e-go-test (standalone & cluster): success
✅ - e2e-cpp-test (standalone & cluster): success
✅ - e2e-csharp-test (standalone & cluster): success
✅ - e2e-nodejs-test (standalone & cluster): success
✅ - e2e-python-test (standalone & cluster): success
✅ - clean (standalone & cluster & standalone_auth): success