Missing source code for google_guest_agent_manager and google_guest_compat_manager

The source tree contains service files for `google-guest-agent-manager.service` and `google-guest-compat-manager.service` while the Go source code for both daemons is missing.

Also, depending on which revision is checked out, the service file `google-startup-scripts.service` sometimes adds a dependency on `google-guest-agent-manager.service` and sometimes not.

Could you please add the sources for these two daemons or at least remove the references to them? It's rather confusing for downstream packagers to work on the source when half the source is missing.

Inspect google-guest-agent-manager.service, google-guest-compat-manager.service, and google-startup-scripts.service in the source tree, then compare the revisions where the startup dependency differs. The issue is done when both daemons have corresponding Go sources or all references are removed, and the startup service dependency is consistent.

Written by the indexing model from the issue text.