Fix Status Page active status and remove unused StatusPageSetting

In
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/28966
we've removed the beta feature flag to make Status Page
generally available.

Thereafter, in
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/29655
we've moved StatusPageSetting to StatusPage::ProjectSetting.

Apparently, we've missed to remove this model and just added
`StatusPage::ProjectSetting`.

Addionally, due to a wrong resolution of a merge conflict we've
added back the beta feature flag to the new model
StatusPage::ProjectSetting. This made the Status Page setting page
behave weirdly: It showed up but users weren't able to activate.

This commits fixes both issues:
* Remove unused StatusPageSetting model
* Remove beta feature flag from StatusPage::ProjectSetting

ee/app/models/status_page/project_setting.rb

@@ -45,9 +45,7 @@ module StatusPage
     end
 
     def enabled?
-      super &&
-        project&.feature_available?(:status_page) &&
-        project&.beta_feature_available?(:status_page)
+      super && project&.feature_available?(:status_page)
     end
 
     def storage_client

ee/app/models/status_page_setting.rb

-# frozen_string_literal: true
-
-class StatusPageSetting < ApplicationRecord
-  # AWS validations. See https://gitlab.com/gitlab-org/gitlab/-/merge_requests/25863#note_295772553
-  AWS_BUCKET_NAME_REGEXP = /\A[a-z0-9][a-z0-9\-.]*\z/.freeze
-  AWS_ACCESS_KEY_REGEXP  = /\A[A-Z0-9]{20}\z/.freeze
-  AWS_SECRET_KEY_REGEXP  = /\A[A-Za-z0-9\/+=]{40}\z/.freeze
-
-  belongs_to :project
-
-  attr_encrypted :aws_secret_key,
-    mode:      :per_attribute_iv,
-    algorithm: 'aes-256-gcm',
-    key:       Settings.attr_encrypted_db_key_base_32
-
-  before_validation :check_secret_changes
-
-  validates :aws_s3_bucket_name,
-            length: { minimum: 3, maximum: 63 },
-            presence: true,
-            format: { with: AWS_BUCKET_NAME_REGEXP }
-  validates :aws_access_key,
-            presence: true,
-            format: { with: AWS_ACCESS_KEY_REGEXP }
-  validates :aws_secret_key,
-            presence: true,
-            format: { with: AWS_SECRET_KEY_REGEXP }
-  validates :project, :aws_region, :encrypted_aws_secret_key,
-            presence: true
-  validates :enabled, inclusion: { in: [true, false] }
-
-  scope :enabled, -> { where(enabled: true) }
-
-  def masked_aws_secret_key
-    return if aws_secret_key.blank?
-
-    '*' * 40
-  end
-
-  def enabled?
-    super && project&.feature_available?(:status_page)
-  end
-
-  def storage_client
-    return unless enabled?
-
-    StatusPage::Storage::S3Client.new(
-      region: aws_region,
-      bucket_name: aws_s3_bucket_name,
-      access_key_id: aws_access_key,
-      secret_access_key: aws_secret_key
-    )
-  end
-
-  private
-
-  def check_secret_changes
-    return unless masked_aws_secret_key == aws_secret_key
-
-    restore_attributes [:aws_secret_key, :encrypted_aws_secret_key, :encrypted_aws_secret_key_iv]
-  end
-end