fixed qemu guest agent check for alpine

alpine/alpine-essentials.sh

@@ -14,23 +14,15 @@ apk update && apk upgrade
 apk add nano sudo pwgen curl wget git bash-doc bash-completion openssh iputils restic --no-cache
 
 # check if vm or lxc
-if [[ ! -d /dev/disk/by-id ]]
+if [[ ! -f /dev/.lxc-boot-id ]]
     then
         apk add qemu-guest-agent
         rc-update add qemu-guest-agent
         rc-service qemu-guest-agent start
     else
-        isInFile=$(ls /dev/disk/by-id | grep -c "QEMU")
-            if [ $isInFile -eq 0 ]
-                then
-                    rc-service qemu-guest-agent stop
-                    rc-update del qemu-guest-agent
-                    apk del qemu-guest-agent
-                else
-                    apk add qemu-guest-agent
-                    rc-update add qemu-guest-agent
-                    rc-service qemu-guest-agent start
-            fi
+        rc-service qemu-guest-agent stop
+        rc-update del qemu-guest-agent
+        apk del qemu-guest-agent
 fi
 
 # change default shell to bash