Removed unused values, functions in InstancePresenter

• Removed:
- unused values, functions in InstancePresenter

app/presenters/instance_presenter.rb

@@ -2,17 +2,12 @@
 
 class InstancePresenter
   delegate(
-    :site_contact_email,
     :site_title,
     :site_short_description,
     :site_description,
     to: Setting
   )
 
-  def sample_accounts
-    Rails.cache.fetch('sample_accounts', expires_in: 12.hours) { Account.discoverable.popular.limit(3) }
-  end
-
   def version_number
     GabSocial::Version
   end
@@ -20,9 +15,5 @@ class InstancePresenter
   def source_url
     GabSocial::Version.source_url
   end
-
-  def thumbnail
-    @thumbnail ||= Rails.cache.fetch('site_uploads/thumbnail') { SiteUpload.find_by(var: 'thumbnail') }
-  end
   
 end