44463 Revert “Demonstrate that artifact invalidation works” (cla: yes, team)

44466 Update dartdoc to 0.29.1 (cla: yes, team)

44467 Make sure all our .dart files have license headers (a: accessibility, cla: yes, d: examples, f: cupertino, f: material design, team, team: gallery)

44468 Fix test for null flutter root (cla: yes, tool)

44469 Deprecation cleanup in flutter_tools (cla: yes, tool)

44473 l10n tool improvements, stocks app i18n refresh (a: internationalization, cla: yes, d: examples, team)

44479 Adding flutter_goldens tests to misc shards (a: tests, cla: yes, framework, team)