Drop tmp index on emails table again

This change drops the tmp_index_for_email_unconfirmation_migration index
again in order to make the structure.sql file consistent. A previous
commit already dropped the index, however for some reason the
structure.sql file was still containing the index.

changelogs/unreleased/drop-tmp-index-on-emails-again.yml

+---
+title: Drop tmp_index_for_email_unconfirmation index from the emails table again
+merge_request: 51440
+author:
+type: other

db/migrate/20210112084512_drop_tmp_index_on_emails_again.rb

+# frozen_string_literal: true
+
+class DropTmpIndexOnEmailsAgain < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  EMAIL_INDEX_NAME = 'tmp_index_for_email_unconfirmation_migration'
+
+  disable_ddl_transaction!
+
+  def up
+    remove_concurrent_index_by_name(:emails, EMAIL_INDEX_NAME)
+  end
+
+  def down
+    add_concurrent_index(:emails, :id, where: 'confirmed_at IS NOT NULL', name: EMAIL_INDEX_NAME)
+  end
+end

db/schema_migrations/20210112084512

+e8e26d49a8292e31ef0ea88a0262f0386b8deda83658ea4de7d464d79c5428e4
\ No newline at end of file

db/structure.sql

@@ -23297,8 +23297,6 @@ CREATE INDEX temporary_index_vulnerabilities_on_id ON vulnerabilities USING btre
 
 CREATE UNIQUE INDEX term_agreements_unique_index ON term_agreements USING btree (user_id, term_id);
 
-CREATE INDEX tmp_index_for_email_unconfirmation_migration ON emails USING btree (id) WHERE (confirmed_at IS NOT NULL);
-
 CREATE INDEX tmp_index_oauth_applications_on_id_where_trusted ON oauth_applications USING btree (id) WHERE (trusted = true);
 
 CREATE INDEX tmp_index_on_vulnerabilities_non_dismissed ON vulnerabilities USING btree (id) WHERE (state <> 2);