Remove deprecated GET /api/v1/search API (#11823)

Use `GET /api/v2/search` instead

app/serializers/rest/search_serializer.rb

@@ -1,12 +1,7 @@
 # frozen_string_literal: true
 
 class REST::SearchSerializer < ActiveModel::Serializer
-  attributes :hashtags
-
   has_many :accounts, serializer: REST::AccountSerializer
   has_many :statuses, serializer: REST::StatusSerializer
-
-  def hashtags
-    object.hashtags.map(&:name)
-  end
+  has_many :hashtags, serializer: REST::TagSerializer
 end

app/serializers/rest/v2/search_serializer.rb

@@ -1,7 +0,0 @@
-# frozen_string_literal: true
-
-class REST::V2::SearchSerializer < ActiveModel::Serializer
-  has_many :accounts, serializer: REST::AccountSerializer
-  has_many :statuses, serializer: REST::StatusSerializer
-  has_many :hashtags, serializer: REST::TagSerializer
-end