Add present_on_default_branch to Vulnerabilites

This column will be used to filter out Vulnerabilites that are shown in
the Vulnerabiliy Report section of Security & Compliance section

Changelog: added

db/migrate/20210623123722_add_present_on_default_branch_to_vulnerabilities.rb

+# frozen_string_literal: true
+
+class AddPresentOnDefaultBranchToVulnerabilities < ActiveRecord::Migration[6.1]
+  include Gitlab::Database::MigrationHelpers
+
+  def up
+    with_lock_retries do
+      add_column :vulnerabilities, :present_on_default_branch, :boolean, default: true, null: false
+    end
+  end
+
+  def down
+    with_lock_retries do
+      remove_column :vulnerabilities, :present_on_default_branch
+    end
+  end
+end

db/schema_migrations/20210623123722

+af58377b87f7e0fb4709637f96b24a4075322d0d8cf87dfaf5bf8e0f8a9372e0
\ No newline at end of file

db/structure.sql

@@ -18924,7 +18924,8 @@ CREATE TABLE vulnerabilities (
     confirmed_at timestamp with time zone,
     dismissed_at timestamp with time zone,
     dismissed_by_id bigint,
-    resolved_on_default_branch boolean DEFAULT false NOT NULL
+    resolved_on_default_branch boolean DEFAULT false NOT NULL,
+    present_on_default_branch boolean DEFAULT true NOT NULL
 );
 
 CREATE SEQUENCE vulnerabilities_id_seq