79323 Revert “Mark flutter_gallery__transition_perf_e2e_ios32 flaky” (cla: yes, team)

79324 Mark docs tests unflaky (cla: yes, team, waiting for tree to go green)

79325 only cache release manifest files for 60 seconds (cla: yes, team)

79329 fix tree (cla: yes, team)

79332 Point gallery test data to FLUTTER_TEST_OUTPUTS_DIR (cla: yes, team, team: infra, waiting for tree to go green)

79338 Allow writing startup_info.json to somewhere other than the build dir (cla: yes, tool, waiting for tree to go green)

79342 Migrate code_signing to null safety (a: null-safety, cla: yes, team, tool)