Issue #2554151 by stefan.r, Gábor Hojtsy, plach, dawehner, csg: Test content/configuration in update database dump

Issue #2558247 by dawehner, catch, mradcliffe, jhedstrom, Berdir, jibran, effulgentsia, webchick: Remove rebuildAll() and module install from UpdatePathTestBase

Issue #2555183 by jhedstrom, Gábor Hojtsy, mikeryan, stefan.r, xjm: Fix the filled update tests, they are broken

Issue #2551341 by stefan.r: Update test database dump should be based on beta 12 and contain content