move method body and remove fetch_content_type method

I was thinking this method shouldn't be in Media, talking to Caio he suggested
this shouldn't be it's own method, since it's only used here.

app/models/media.rb

@@ -80,7 +80,7 @@ def domain
   def self.find_or_create_from_original_claim(claim, project_media_team)
     if claim.match?(/\A#{URI::DEFAULT_PARSER.make_regexp(['http', 'https'])}\z/)
       uri = URI.parse(claim)
-      content_type = fetch_content_type(uri)
+      content_type = Net::HTTP.get_response(uri)['content-type']
       ext = File.extname(uri.path)
 
       case content_type
@@ -130,11 +130,6 @@ def set_original_claim_hash
     self.original_claim_hash = Digest::MD5.hexdigest(original_claim) unless self.original_claim.blank?
   end
 
-  def self.fetch_content_type(uri)
-    response = Net::HTTP.get_response(uri)
-    response['content-type']
-  end
-
   def self.create_uploaded_file_media_from_original_claim(media_type, url, ext)
     klass = media_type.constantize
     file = download_file(url, ext)