The train command does nothing and was originally added to provide a no-output default for generating app-jit snapshots. The inject-plugins command is only for a repo-only analysis check, which is not necessary since we regenerate during pub get.
#29805
Integration tests must only go through the real file system/process manager/platform. The global indirection makes this code harder to understand than if it directly referred to the concrete instances that are being used.
Update the integration shard to use a const instance of a LocalFIleSystem, LocalProcessManager, and LocalPlatform. Remove global usage and apply testWithoutContext.
This command was previously used by the re-entrant build scripts in xcode_backend.sh and build.gradle. These have since been refactored to use flutter assemble.
Deprecation the command in preparation for removal in a future release of flutter. The only current use is a test on HHH
