Add `has_vulnerabilities` column to project_settings table

We will use this value to identify projects using security dashboard.

db/migrate/20201022191817_add_has_vulnerabilities_into_project_settings.rb

+# frozen_string_literal: true
+
+class AddHasVulnerabilitiesIntoProjectSettings < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def up
+    with_lock_retries do
+      add_column :project_settings, :has_vulnerabilities, :boolean, default: false, null: false
+    end
+  end
+
+  def down
+    with_lock_retries do
+      remove_column :project_settings, :has_vulnerabilities
+    end
+  end
+end

db/migrate/20201022192254_index_project_settings_on_project_id_partially.rb

+# frozen_string_literal: true
+
+class IndexProjectSettingsOnProjectIdPartially < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  INDEX_NAME = 'index_project_settings_on_project_id_partially'
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index :project_settings, :project_id, name: INDEX_NAME, where: 'has_vulnerabilities IS TRUE'
+  end
+
+  def down
+    remove_concurrent_index_by_name :project_settings, INDEX_NAME
+  end
+end

db/schema_migrations/20201022191817

+205cb628e9637bcd1acb90c5211b71b51015fa5f50aadcacd5fbafc4f09c00d0
\ No newline at end of file

db/schema_migrations/20201022192254

+9f942de6f83629a144e9d460b4bed7a246afe95275b5913745109fc0ab9dacc1
\ No newline at end of file

db/structure.sql

@@ -15190,6 +15190,7 @@ CREATE TABLE project_settings (
     allow_merge_on_skipped_pipeline boolean,
     squash_option smallint DEFAULT 3,
     has_confluence boolean DEFAULT false NOT NULL,
+    has_vulnerabilities boolean DEFAULT false NOT NULL,
     CONSTRAINT check_bde223416c CHECK ((show_default_award_emojis IS NOT NULL))
 );
 
@@ -21460,6 +21461,8 @@ CREATE UNIQUE INDEX index_project_repository_states_on_project_id ON project_rep
 
 CREATE INDEX index_project_repository_storage_moves_on_project_id ON project_repository_storage_moves USING btree (project_id);
 
+CREATE INDEX index_project_settings_on_project_id_partially ON project_settings USING btree (project_id) WHERE (has_vulnerabilities IS TRUE);
+
 CREATE UNIQUE INDEX index_project_settings_on_push_rule_id ON project_settings USING btree (push_rule_id);
 
 CREATE INDEX index_project_statistics_on_namespace_id ON project_statistics USING btree (namespace_id);