mkosi: Reduce postinst script indentation

mkosi.postinst

@@ -1,8 +1,11 @@
 #!/bin/sh
 # SPDX-License-Identifier: LGPL-2.1-or-later
 
-if [ "$1" = "final" ]; then
-    if [ -n "$SANITIZERS" ]; then
+if [ "$1" = "build" ]; then
+    exit 0
+fi
+
+if [ -n "$SANITIZERS" ]; then
     LD_PRELOAD=$(ldd /usr/lib/systemd/systemd | grep libasan.so | awk '{print $3}')
 
     mkdir -p /etc/systemd/system.conf.d
@@ -42,24 +45,23 @@ EOF
 
     # `systemd-hwdb update` takes > 50s when built with sanitizers so let's not run it by default.
     systemctl mask systemd-hwdb-update.service
-    fi
+fi
 
-    # Make sure dnsmasq.service doesn't start on boot on Debian/Ubuntu.
-    rm -f /etc/systemd/system/multi-user.target.wants/dnsmasq.service
+# Make sure dnsmasq.service doesn't start on boot on Debian/Ubuntu.
+rm -f /etc/systemd/system/multi-user.target.wants/dnsmasq.service
 
-    if [ -n "$IMAGE_ID" ] ; then
+if [ -n "$IMAGE_ID" ] ; then
     sed -n \
         -i \
         -e '/^IMAGE_ID=/!p' \
         -e "\$aIMAGE_ID=$IMAGE_ID" \
         /usr/lib/os-release
-    fi
+fi
 
-    if [ -n "$IMAGE_VERSION" ] ; then
+if [ -n "$IMAGE_VERSION" ] ; then
     sed -n \
         -i \
         -e '/^IMAGE_VERSION=/!p' \
         -e "\$aIMAGE_VERSION=$IMAGE_VERSION" \
         /usr/lib/os-release
-    fi
 fi