Completely remove old hints connected to the execution environment

app/models/execution_environment.rb

@@ -10,7 +10,6 @@ class ExecutionEnvironment < ApplicationRecord
 
   has_many :exercises
   belongs_to :file_type
-  has_many :hints
   has_many :error_templates
 
   scope :with_exercises, -> { where('id IN (SELECT execution_environment_id FROM exercises)') }

app/models/hint.rb

@@ -1,17 +0,0 @@
-class Hint < ApplicationRecord
-  belongs_to :execution_environment
-
-  validates :execution_environment_id, presence: true
-  validates :locale, presence: true
-  validates :message, presence: true
-  validates :name, presence: true
-  validates :regular_expression, presence: true
-
-  def self.nested_resource?
-    true
-  end
-
-  def to_s
-    name
-  end
-end