68034 [NNBD] Migrate some Widgets tests (a: tests, cla: yes, framework, team, waiting for tree to go green)

68036 Revert “prevent pageView scrolling when calling ensureVisible” (cla: yes, framework)

68037 Migrate more tests (cla: yes, framework)

68038 Mark unusuallyLongTimeout as internal (a: tests, cla: yes, framework, waiting for tree to go green)

68043 Reland “More EditableText docs (#66864)” (cla: yes, framework, waiting for tree to go green)

68065 Improve performance of collectAllElements (a: tests, cla: yes, framework, perf: speed, severe: performance, t: flutter driver, team, waiting for tree to go green)