BURs: fix normalization of uppercase characters in scripts.

Only downcase tags in aliases, implications, and category change
commands. Don't downcase mass update commands. Mass updates are
potentially case sensitive (for example: `mass update source:imageboard -> source:Imageboard`).

app/models/bulk_update_request.rb

@@ -8,7 +8,6 @@ class BulkUpdateRequest < ApplicationRecord
   belongs_to :forum_post, optional: true
   belongs_to :approver, optional: true, class_name: "User"
 
-  before_validation :normalize_text
   validates_presence_of :reason, on: :create
   validates_presence_of :script
   validates_presence_of :title, if: ->(rec) {rec.forum_topic_id.blank?}
@@ -117,10 +116,6 @@ class BulkUpdateRequest < ApplicationRecord
   extend SearchMethods
   include ApprovalMethods
 
-  def normalize_text
-    self.script = script.downcase
-  end
-
   def update_tags
     self.tags = processor.affected_tags
   end