[skip changelog] Remove obsolete go generate directive (#1341)

In the early days of Arduino CLI's gRPC interface, the protocol buffer compilation was done via `go generate`, configured
by a directive comment. The `protoc:compile` task is now used instead, but the old directive was left in place, where it
became outdated through changes to the repository structure.

This directive no longer functions or serves a purpose and might cause confusion to contributors. So it should be removed.

Author: per1234

commands/daemon/daemon.go

@@ -15,8 +15,6 @@
 
 package daemon
 
-//go:generate protoc -I arduino --go_out=plugins=grpc:arduino arduino/arduino.proto
-
 import (
 	"context"
 	"io"