This fixes the image build error where, after having changed the build
command to use the root of the repo instead of ./src, the Go toolchain
is unable to find any .go files to build.
The grebedoc.dev infrastructure is no longer directly tied to
the container built from this repository, so we don't have to
pollute the configuration with Fly.io-isms.
Fly.io starts routing requests to the VM the moment it becomes
reachable (listens on its service ports) even if it is not ready yet.
This causes transient failures on machine startup.
