distro/rhel9: update image-installer to new definition

Add the image function and remove the pipeline function.
Remove the build package set.

The image function (imageInstallerImage) was adapted from the same one
in Fedora.

internal/distro/rhel9/bare_metal.go

@@ -35,7 +35,6 @@ var (
 		filename: "installer.iso",
 		mimeType: "application/x-iso9660-image",
 		packageSets: map[string]packageSetFunc{
-			buildPkgsKey:     anacondaBuildPackageSet,
 			osPkgsKey:        bareMetalPackageSet,
 			installerPkgsKey: anacondaPackageSet,
 		},
@@ -45,7 +44,7 @@ var (
 		rpmOstree:        false,
 		bootISO:          true,
 		bootable:         true,
-		pipelines:        imageInstallerPipelines,
+		image:            imageInstallerImage,
 		buildPipelines:   []string{"build"},
 		payloadPipelines: []string{"os", "anaconda-tree", "bootiso-tree", "bootiso"},
 		exports:          []string{"bootiso"},

internal/distro/rhel9/images.go

@@ -325,3 +325,32 @@ func edgeRawImage(workload workload.Workload,
 
 	return img, nil
 }
+
+func imageInstallerImage(workload workload.Workload,
+	t *imageType,
+	customizations *blueprint.Customizations,
+	options distro.ImageOptions,
+	packageSets map[string]rpmmd.PackageSet,
+	containers []container.Spec,
+	rng *rand.Rand) (image.ImageKind, error) {
+
+	img := image.NewImageInstaller()
+
+	img.Platform = t.platform
+	img.OSCustomizations = osCustomizations(t, packageSets[osPkgsKey], options, containers, customizations)
+	img.ExtraBasePackages = packageSets[installerPkgsKey]
+	img.Users = users.UsersFromBP(customizations.GetUsers())
+	img.Groups = users.GroupsFromBP(customizations.GetGroups())
+
+	d := t.arch.distro
+
+	img.ISOLabelTempl = d.isolabelTmpl
+	img.Product = d.product
+	img.OSName = "redhat"
+	img.OSVersion = d.osVersion
+	img.Release = fmt.Sprintf("%s %s", d.product, d.osVersion)
+
+	img.Filename = t.Filename()
+
+	return img, nil
+}