Remove storage_version column from snippets

In this commit the storage_version column is
removed from the snippets table. It was wrongly
added and never needed

changelogs/unreleased/fj-remove-storage-version-column-from-snippets.yml

+---
+title: Remove storage_version column from snippets
+merge_request: 23315
+author:
+type: other

db/post_migrate/20200120083607_remove_storage_version_column_from_snippets.rb

+# frozen_string_literal: true
+
+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class RemoveStorageVersionColumnFromSnippets < ActiveRecord::Migration[5.2]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    return unless column_exists?(:snippets, :storage_version)
+
+    remove_column :snippets, :storage_version
+  end
+
+  def down
+    return if column_exists?(:snippets, :storage_version)
+
+    add_column_with_default( # rubocop:disable Migration/AddColumnWithDefault
+      :snippets,
+      :storage_version,
+      :integer,
+      default: 2,
+      allow_null: false
+    )
+  end
+end

db/schema.rb

@@ -3843,7 +3843,6 @@ ActiveRecord::Schema.define(version: 2020_01_21_132641) do
     t.string "encrypted_secret_token_iv", limit: 255
     t.boolean "secret", default: false, null: false
     t.string "repository_storage", limit: 255, default: "default", null: false
-    t.integer "storage_version", default: 2, null: false
     t.index ["author_id"], name: "index_snippets_on_author_id"
     t.index ["content"], name: "index_snippets_on_content_trigram", opclass: :gin_trgm_ops, using: :gin
     t.index ["created_at"], name: "index_snippets_on_created_at"

lib/gitlab/import_export/import_export.yml

@@ -178,7 +178,6 @@ excluded_attributes:
     - :encrypted_secret_token
     - :encrypted_secret_token_iv
     - :repository_storage
-    - :storage_version
   merge_request_diff:
     - :external_diff
     - :stored_externally