TEST-13-NSPAWN: Use timeout --foreground in two more places

test/units/TEST-13-NSPAWN.nspawn-oci.sh

@@ -395,7 +395,7 @@ touch /opt/readonly/foo && exit 1
 
 exit 0
 EOF
-timeout 30 systemd-nspawn --oci-bundle="$OCI"
+timeout --foreground 30 systemd-nspawn --oci-bundle="$OCI"
 
 # Test a couple of invalid configs
 INVALID_SNIPPETS=(

test/units/TEST-13-NSPAWN.nspawn.sh

@@ -578,7 +578,7 @@ ip link | grep wl-renamed1
 EOF
     fi
 
-    timeout 30 systemd-nspawn --directory="$root"
+    timeout --foreground 30 systemd-nspawn --directory="$root"
 
     # And now for stuff that needs to run separately
     #