refactor: clear the template cache after uninstalling the theme

[guqing]

What type of PR is this?

/kind improvement
/area core
/milestone 2.20.x

What this PR does / why we need it:

卸载主题之后清理模板缓存

此问题是 #2970 的遗留问题

Does this PR introduce a user-facing change?

None

[f2c-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[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 SonarQube Cloud

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 57.20%. Comparing base (eff73dc) to head (639bfed).
Report is 82 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #7174      +/-   ##
============================================
+ Coverage     56.99%   57.20%   +0.20%     
- Complexity     3999     4047      +48     
============================================
  Files           714      719       +5     
  Lines         24110    24349     +239     
  Branches       1585     1598      +13     
============================================
+ Hits          13742    13929     +187     
- Misses         9756     9803      +47     
- Partials        612      617       +5     

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