Fix the problem of being able to configure invalid external URL

[JohnNiang]

What type of PR is this?

/kind bug
/area core
/milestone 2.20.x

What this PR does / why we need it:

This PR makes users not be able to configure a invalid external URL like https:www/halo.run even if it is an valid URL format.

Which issue(s) this PR fixes:

Fixes #6837

Does this PR introduce a user-facing change?

修复可配置无效的外部访问地址的问题

[sonarcloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[codecov]

Codecov Report

Attention: Patch coverage is 81.81818% with 2 lines in your changes missing coverage. Please review.

Project coverage is 57.06%. Comparing base (d7aba83) to head (442e3aa).
Report is 29 commits behind head on main.

Files with missing lines	Patch %	Lines
.../run/halo/app/infra/properties/HaloProperties.java	81.81%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6840      +/-   ##
============================================
+ Coverage     57.03%   57.06%   +0.02%     
- Complexity     3978     3999      +21     
============================================
  Files           713      714       +1     
  Lines         23992    24083      +91     
  Branches       1570     1583      +13     
============================================
+ Hits          13685    13742      +57     
- Misses         9696     9729      +33     
- Partials        611      612       +1     

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[ruibaby]

/lgtm

[f2c-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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