perf: add caching for system configuration fetcher to enhance performance

[guqing]

What type of PR is this?

/kind improvement
/area core
/milestone 2.20.x

What this PR does / why we need it:

为系统配置获取增加缓存以提高路由和主题模板渲染的速度

Special notes for your reviewer:

1. 系统能正确初始化
2. 测试修改系统配置后 http://localhost:8090/actuator/globalinfo 和主题端 ${site} 是否都是新的
3. 更改了文章路由规则后能正确调整到新的规则

Does this PR introduce a user-facing change?

为系统配置的获取增加缓存以提高路由和主题模板渲染的速度

[codecov]

Codecov Report

Attention: Patch coverage is 89.18919% with 4 lines in your changes missing coverage. Please review.

Project coverage is 57.26%. Comparing base (eff73dc) to head (8d6ea2f).
Report is 70 commits behind head on main.

Files with missing lines	Patch %	Lines
...pp/infra/SystemConfigurableEnvironmentFetcher.java	94.11%	1 Missing and 1 partial ⚠️
...pp/core/endpoint/console/SystemConfigEndpoint.java	0.00%	1 Missing ⚠️
...halo/app/security/preauth/SystemSetupEndpoint.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #7100      +/-   ##
============================================
+ Coverage     56.99%   57.26%   +0.26%     
- Complexity     3999     4023      +24     
============================================
  Files           714      713       -1     
  Lines         24110    24232     +122     
  Branches       1585     1593       +8     
============================================
+ Hits          13742    13876     +134     
+ Misses         9756     9741      -15     
- Partials        612      615       +3     

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[ruibaby]

/lgtm

[JohnNiang]

/approve

[f2c-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JohnNiang

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