Remove releases author_id index

We recently added index on (author_id, id, created_at) which covers this one

Changelog: performance

db/migrate/20211026143238_remove_index_releases_on_author_id.rb

+# frozen_string_literal: true
+
+class RemoveIndexReleasesOnAuthorId < Gitlab::Database::Migration[1.0]
+  INDEX_NAME = 'index_releases_on_author_id'
+
+  disable_ddl_transaction!
+
+  def up
+    remove_concurrent_index_by_name :releases, INDEX_NAME
+  end
+
+  def down
+    add_concurrent_index :releases, [:author_id], name: INDEX_NAME
+  end
+end

db/schema_migrations/20211026143238

+6b1377dd7e9b78a35c2f5635d2d11f5fe254aa772576510b41fcf1e03ad56c87
\ No newline at end of file

db/structure.sql

@@ -26446,8 +26446,6 @@ CREATE UNIQUE INDEX index_release_links_on_release_id_and_name ON release_links
 
 CREATE UNIQUE INDEX index_release_links_on_release_id_and_url ON release_links USING btree (release_id, url);
 
-CREATE INDEX index_releases_on_author_id ON releases USING btree (author_id);
-
 CREATE INDEX index_releases_on_author_id_id_created_at ON releases USING btree (author_id, id, created_at);
 
 CREATE INDEX index_releases_on_project_id_and_tag ON releases USING btree (project_id, tag);