Some "top-level" orchestrator builds only kick off sub-builds and then do nothing but wait for the results. Mac mac_unopt is an example of this:

Note there are no "Global generators" or tests.

GitHub currently only allows reruns on these top-level builds when there's a failure in the subbuild. In the case of mac_unopt that means all the sub-builds are re-run, even though most of them succeeded (example). Rerunning all of them ties up CI resources and makes the rerun longer, if the failing test isn't the long-pole of the top-level build total time. It also means the top-level orchestrator build idles bot while it waits on the builds to finish.

mac_ios_engine is an example of a build that can't be trivially replaced by it subviews (like ci/ios_debug_sim) because it has generators that operate on the archives:
https://github.com/flutter/engine/blob/38e37ce9879b2efe4890a8d09f4207dc5686a1bd/ci/builders/mac_ios_engine.json#L488C6-L488C16

This proposes removing all top-level builds that only kick off subbuilds, and hoisting the sub-builds into the .ci.yaml.

• Linux clangd Remove Linux orchestrator builds that only kick off one other build and wait engine#55186
• Linux mac_clangd Add standalone 'Mac clangd' builder to replace 'Linux mac_clangd' orchestrator engine#56014
• Linux linux_android_emulator*
• Linux linux_android_emulator_skia_tests Remove Linux orchestrator builds that only kick off one other build and wait engine#55186
• Linux linux_android_emulator_skia_tests_34 Remove Linux orchestrator builds that only kick off one other build and wait engine#55186
• Linux linux_arm_host_engine
• Linux linux_fuchsia_tests
• Linux linux_host_desktop_engine
• linux_unopt
• linux_web_engine
• local_engine
• mac_android_aot_engine
• mac_unopt
• windows_android_aot_engine
• windows_arm_host_engine
• windows_arm_host_engine

cc @zanderso @jtmcdole