Fix the problem of not being able to create PAT for OAuth2 user

[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 refactors check of whether the current user is a real user to fix the problem of not being able to create PAT for OAuth2 user.

Does this PR introduce a user-facing change?

修复通过 OAuth2 登录之后无法正常创建和恢复个人令牌的问题

[sonarcloud]

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

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 57.00%. Comparing base (eff73dc) to head (fdb84da).
Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
...hentication/pat/impl/UserScopedPatHandlerImpl.java	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #6870   +/-   ##
=========================================
  Coverage     56.99%   57.00%           
- Complexity     3999     4003    +4     
=========================================
  Files           714      714           
  Lines         24110    24174   +64     
  Branches       1585     1593    +8     
=========================================
+ Hits          13742    13780   +38     
- Misses         9756     9780   +24     
- Partials        612      614    +2     

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[guqing]

/lgtm

[f2c-ci-robot]

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