chore: split dbus-send and string maniplation

We're running the script with `-e`; by splitting these two things into
two steps we allow the script to exit if it fails to perform
`dbus-send`, i.e. if mender-authd is not running.

Signed-off-by: Daniel Skinstad Drabitzius <daniel.drabitzius@northern.tech>

Author: danielskinstad

src/mender-inventory-mender-configure

@@ -30,13 +30,14 @@ if ! [ -f "$CONFIG" ]; then
 fi
 
 # Fetch Authentication token and server from Mender Auth Manager.
-DBUS_REPLY="$(dbus-send \
-                        --system \
-                        --print-reply \
-                        --dest=io.mender.AuthenticationManager \
-                        /io/mender/AuthenticationManager \
-                        io.mender.Authentication1.GetJwtToken \
-                        | sed -ne '/^ *string ".*" *$/ {s/^ *string "\(.*\)" *$/\1/; p}')"
+DBUS_RAW=$(dbus-send \
+    --system \
+    --print-reply \
+    --dest=io.mender.AuthenticationManager \
+    /io/mender/AuthenticationManager \
+    io.mender.Authentication1.GetJwtToken)
+
+DBUS_REPLY=$(echo "$DBUS_RAW" | sed -ne '/^ *string ".*" *$/ {s/^ *string "\(.*\)" *$/\1/; p}')
 
 AUTH_TOKEN="$(echo "$DBUS_REPLY" | sed -ne '1p')"
 SERVER="$(echo "$DBUS_REPLY" | sed -ne '2p')"