51591 Add explicit casts to for-in-dynamic. (a: tests, cla: yes, framework, tool, waiting for tree to go green)

51593 [flutter_tools] clean-ups to linux doctor test (cla: yes, tool, waiting for tree to go green)

51597 [flutter_tools] remove LinuxWorkflow from injection and clean up tests (cla: yes, tool)

51600 Roll engine 2914e4ddf6c7..a16d97e507c8 (4 commits) (cla: yes, waiting for tree to go green)

51602 Update gen_l10n tool to require base locale; Stocks app refresh (a: internationalization, cla: yes, severe: crash, team, waiting for tree to go green)