fix: Remove unused frontend modules and fix incorrect UT on backend

[o-kopysov]

Description

Current PR removes unused frontend modules and fixes incorrect UT on backend.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Code cleanup/refactoring
• Documentation update
• This change requires a documentation update
• CI system update
• Test Coverage update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (d1ded3a) 81.69% compared to head (eeb9d47) 81.74%.

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #296      +/-   ##
============================================
+ Coverage     81.69%   81.74%   +0.04%     
  Complexity      394      394              
============================================
  Files            48       48              
  Lines          1519     1517       -2     
  Branches        182      182              
============================================
- Hits           1241     1240       -1     
+ Misses          198      197       -1     
  Partials         80       80              

Files	Coverage Δ
.../main/java/com/lpvs/service/LPVSGitHubService.java	82.17% <ø> (ø)
src/main/java/com/lpvs/service/OAuthService.java	96.87% <100.00%> (+2.75%)	⬆️

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[tiokim]

LGTM