fix: username length validation in user creation form is not working

[ruibaby]

What type of PR is this?

/area ui
/kind bug
/milestone 2.20.x

What this PR does / why we need it:

修复创建用户表单的用户名长度校验不生效的问题。

Does this PR introduce a user-facing change?

修复创建用户表单的用户名长度校验不生效的问题。

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

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

See analysis details on SonarCloud

[JohnNiang]

/lgtm

[guqing]

/lgtm

[f2c-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: guqing, JohnNiang

The full list of commands accepted by this bot can be found here.

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Needs approval from an approver in each of these files:

• ui/OWNERS [JohnNiang,guqing]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 57.03%. Comparing base (d7aba83) to head (18a100d).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #6806   +/-   ##
=========================================
  Coverage     57.03%   57.03%           
  Complexity     3978     3978           
=========================================
  Files           713      713           
  Lines         23992    23992           
  Branches       1570     1570           
=========================================
  Hits          13685    13685           
  Misses         9696     9696           
  Partials        611      611           

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