image: fix kernel options compat in AnacondaOSTreeInstaller

The fedora `iot-installer` image sets default image type
kernel options that were previously not honored by the
image type. With the unification of the installer kernel
options it is no honored which leads to a manifest diff.

It is not clear if we want these kernel options or not
but this commit is conservative and keeps the old
behavior by just unsetting the kernel options in the
"iot-installer" image options.

Author: mvo5

data/distrodefs/fedora/imagetypes.yaml

@@ -1638,6 +1638,8 @@ image_types:
     image_config:
       <<: *image_config_iot_enabled_services
       locale: "en_US.UTF-8"
+      # iot-installer is not using the default ostree kernel options
+      kernel_options:
     package_sets:
       installer:
         - *anaconda_pkgset

pkg/image/anaconda_ostree_installer.go

@@ -100,10 +100,12 @@ func (img *AnacondaOSTreeInstaller) InstantiateManifest(m *manifest.Manifest,
 	if img.Kickstart.Path == "" {
 		img.Kickstart.Path = osbuild.KickstartPathOSBuild
 	}
-	bootTreePipeline.KernelOpts = []string{fmt.Sprintf("inst.stage2=hd:LABEL=%s", img.InstallerCustomizations.ISOLabel), fmt.Sprintf("inst.ks=hd:LABEL=%s:%s", img.InstallerCustomizations.ISOLabel, img.Kickstart.Path)}
+	kernelOpts := []string{fmt.Sprintf("inst.stage2=hd:LABEL=%s", img.InstallerCustomizations.ISOLabel), fmt.Sprintf("inst.ks=hd:LABEL=%s:%s", img.InstallerCustomizations.ISOLabel, img.Kickstart.Path)}
 	if anacondaPipeline.InstallerCustomizations.FIPS {
-		bootTreePipeline.KernelOpts = append(bootTreePipeline.KernelOpts, "fips=1")
+		kernelOpts = append(kernelOpts, "fips=1")
 	}
+	kernelOpts = append(kernelOpts, img.InstallerCustomizations.KernelOptionsAppend...)
+	bootTreePipeline.KernelOpts = kernelOpts
 
 	var subscriptionPipeline *manifest.Subscription
 	if img.Subscription != nil {