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

[imbajin]

Purpose of the PR

• enhance [Bug] Dynamic create multi graph error with restful api in 1.2.0 #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).
• 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
• Other affects (typed here)
• Nope

Documentation Status

• Doc - TODO
• Doc - Done
• Doc - No Need

[codecov]

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 ⚠️
...ain/java/org/apache/hugegraph/util/Reflection.java	41.17%	9 Missing and 1 partial ⚠️
...che/hugegraph/api/filter/AuthenticationFilter.java	0.00%	3 Missing ⚠️
...rg/apache/hugegraph/auth/HugeFactoryAuthProxy.java	88.46%	3 Missing ⚠️

Additional details and impacted files

@@            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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