Remove unused rails rubocop rules

We consider these rules either return false positives or we don't have a
strong opinion about them.

.rubocop.yml

@@ -18,24 +18,9 @@ Performance/EndWith:
 Performance/StartWith:
   Enabled: true
 
-Rails/ActiveSupportAliases:
-  Enabled: true
-
-Rails/Blank:
-  Enabled: true
-
 Rails/CreateTableWithTimestamps:
   Enabled: true
 
-Rails/Delegate:
-  Enabled: true
-
-Rails/DelegateAllowBlank:
-  Enabled: true
-
-Rails/DynamicFindBy:
-  Enabled: true
-
 Rails/EnumUniqueness:
   Enabled: true
 
@@ -45,9 +30,6 @@ Rails/EnvironmentComparison:
 Rails/Exit:
   Enabled: true
 
-Rails/FilePath:
-  Enabled: true
-
 Rails/FindBy:
   Enabled: true
 
@@ -63,27 +45,12 @@ Rails/HasManyOrHasOneDependent:
 Rails/InverseOf:
   Enabled: true
 
-Rails/LexicallyScopedActionFilter:
-  Enabled: true
-
 Rails/NotNullColumn:
   Enabled: true
 
-Rails/Output:
-  Enabled: true
-
 Rails/OutputSafety:
   Enabled: true
 
-Rails/Present:
-  Enabled: true
-
-Rails/ReadWriteAttribute:
-  Enabled: true
-
-Rails/RedundantReceiverInWithOptions:
-  Enabled: true
-
 Rails/ReversibleMigration:
   Enabled: true
 
@@ -183,12 +150,6 @@ RSpec/NestedGroups:
   Enabled: true
   Max: 4
 
-RSpec/PredicateMatcher:
-  Enabled: true
-
-Rails/HttpStatus:
-  Enabled: true
-
 RSpec/RepeatedDescription:
   Enabled: true