automation: remove Rust installation on workers from setup-host.sh

setup-local-ssd.sh already has code to install Rust.  It doesn’t need to
be done in setup-host.sh.  Furthermore, for easier interactive use, make
sure CARGO_HOST and RUSTUP_HOME are properly setup when logging onto the
machine as nayduck user.

automation/setup-host.sh

@@ -104,14 +104,9 @@ if [ "$type" = frontend ]; then
 	# different on different machines so this needs to be done manually.
 	# This also needs to be added as a service to systemd so it’s run on
 	# each boot.
-else
-	curl https://sh.rustup.rs -sSf | sudo -u nayduck sh -s -- -y
-	sudo -u nayduck .cargo/bin/rustup target add wasm32-unknown-unknown
-	if [ "$type" = worker ]; then
-		apt-get -y install docker.io
-		usermod -aGdocker nayduck
-		sudo -u nayduck .cargo/bin/cargo install cargo-fuzz
-	fi
+elif [ "$type" = worker ]; then
+	apt-get -y install docker.io
+	usermod -aGdocker nayduck
 fi
 
 case $type in

systemd/setup-local-ssd.sh

@@ -54,6 +54,9 @@ if ! [ -d "$dir/home" ]; then
 		"$CARGO_HOME/bin/rustup" target add wasm32-unknown-unknown
 		"$CARGO_HOME/bin/cargo" install cargo-fuzz
 	'
+	printf "%s='%s'\\n" >>"$dir/home/cargo/env" \
+	       CARGO_HOME "$dir/home/cargo" \
+	       RUSTUP_HOME "$dir/home/rustup"
 fi
 
 if ! [ -d "$dir/docker" ]; then