refact(server): enhance the storage path in RocksDB & clean code

[imbajin]

Purpose of the PR

• enhance #2418 & need doc

Main Changes

Verifying these changes

• [ ] Trivial rework / code cleanup without any test coverage. (No Need)
• [ ] Already covered by existing tests, such as (please modify tests here).
• [x] Need tests and can be verified as follows:
  • xxx

Does this PR potentially affect the following parts?

• [ ] Dependencies (add/update license info & regenerate_dependencies)
• [ ] Modify configurations
• [ ] The public API
• [x] Other affects (typed here)
• [ ] Nope

Documentation Status

• [x] Doc - TODO
• [x] Doc - Done
• [ ] Doc - No Need

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 65.47619% with 29 lines in your changes are missing coverage. Please review.

Project coverage is 66.27%. Comparing base (277f76e) to head (30fc04a).

Files	Patch %	Lines
...apache/hugegraph/security/HugeSecurityManager.java	63.88%	4 Missing and 9 partials :warning:
...ain/java/org/apache/hugegraph/util/Reflection.java	41.17%	9 Missing and 1 partial :warning:
...che/hugegraph/api/filter/AuthenticationFilter.java	0.00%	3 Missing :warning:
...rg/apache/hugegraph/auth/HugeFactoryAuthProxy.java	88.46%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2491 +/- ## ========================================== Coverage 66.26% 66.27% - Complexity 827 982 +155 ========================================== Files 511 511 Lines 42631 42649 +18 Branches 5948 5942 -6 ========================================== + Hits 28251 28267 +16 - Misses 11557 11571 +14 + Partials 2823 2811 -12 ```

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