[engine] migration to luci

[godofredoc]

Remove cirrus tasks already running on LUCI:

• build_and_test_windows_unopt_debug - https://ci.chromium.org/p/flutter/builders/try/Windows%20Host%20Engine
• build_windows_opt_debug - https://ci.chromium.org/p/flutter/builders/try/Windows%20Host%20Engine

[godofredoc]

We can also remove:

• build_fuchsia_artifacts: already covered by https://ci.chromium.org/p/flutter/builders/try/Linux%20Fuchsia
• build_and_test_android_unopt_debug

[godofredoc]

Migration of android unopt build and tests migrated to:

https://chromium-review.googlesource.com/c/chromium/tools/build/+/2152285

Other tests/builds that can also be moved:

• build_and_benchmark_linux_release
• build_and_test_linux_unopt_debug