Simplify .rubocop_rspec.yml.

Library/.rubocop.yml

@@ -14,7 +14,7 @@ AllCops:
   NewCops: enable
   Exclude:
     - 'Homebrew/bin/*'
-    - 'Homebrew/**/vendor/**/*'
+    - 'Homebrew/vendor/**/*'
 
 Cask/Desc:
   Description: 'Ensure that the desc stanza conforms to various content and style checks.'

Library/.rubocop_rspec.yml

@@ -1,17 +1,5 @@
 inherit_from: ./.rubocop.yml
 
-AllCops:
-  Include:
-    - '**/cmd/**/*.rb'
-    - '**/lib/**/*.rb'
-    - '**/spec/**/*.rb'
-  Exclude:
-    - '**/vendor/**/*'
-
-# allow style to be disabled in non-formulae code
-Style/DisableCopsWithinSourceCodeDirective:
-  Enabled: false
-
 # Intentionally disabled as it doesn't fit with our code style.
 RSpec/AnyInstance:
   Enabled: false