Use theforeman-rubocop gem

Choose to inherit from lenient.yml, because wanted to inherit rules
from style_lenient.yml as well, i followed this:
https://github.com/theforeman/theforeman-rubocop?tab=readme-ov-file#not-intrusive-style---lenient

Also drop some cops from the .rubocop.yml config, because that was
present in inherit-gem and added theforeman-rubocop gem.

This is part of Rubocop standerdization, link for the reference:
https://community.theforeman.org/t/standardizing-rubocop-with-theforeman-rubocop/37239

.github/workflows/unit-tests.yml

@@ -10,6 +10,8 @@ jobs:
   rubocop:
     name: Rubocop
     uses: theforeman/actions/.github/workflows/rubocop.yml@v0
+    with:
+      command: bundle exec rubocop --parallel --format github
 
   test:
     name: Tests

.rubocop.yml

@@ -1,19 +1,17 @@
 # TODO: remove this
 inherit_from: .rubocop_todo.yml
 
+inherit_gem:
+  theforeman-rubocop:
+    - lenient.yml
+
 AllCops:
   TargetRubyVersion: 2.7
 
 MethodLength:
   Description: 'Avoid methods longer than 30 lines of code.'
   Max: 30 # default is 10
 
-Documentation:
-  Enabled: false
-
-StringLiterals:
-  Enabled: false
-
 HashSyntax:
   Enabled: false
 
@@ -71,12 +69,6 @@ RedundantReturn:
 SingleLineBlockParams:
   Enabled: false
 
-FormatString:
-  Enabled: false # we use % for i18n
-
-Style/Alias:
-  Enabled: false
-
 Style/MultilineMethodCallBraceLayout:
   Enabled: false