tests: Skip --bootloader flag for UKI images in install-outside-container

For UKI (Unified Kernel Image) images, the boot setup is handled
differently than BLS (Type1) images. UKI images have the kernel,
initrd, and cmdline bundled in a single .efi file at /boot/EFI/Linux/.

When installing a UKI image with --composefs-backend, passing
--bootloader=systemd causes the install to go through the BLS boot
setup path which doesn't work for UKI images.

Fix this by checking the bootType from status and skipping the
--bootloader flag for UKI images, allowing the UKI boot setup
to handle it correctly.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Signed-off-by: Xiaofeng Wang <henrywangxf@me.com>

Author: henrywang

tmt/tests/booted/test-install-outside-container.nu

@@ -31,8 +31,14 @@ let base_args = $"bootc install to-disk --disable-selinux --via-loopback --sourc
 
 let install_cmd = if (tap is_composefs) {
     let st = bootc status --json | from json
-    let bootloader = ($st.status.booted.composefs.bootloader | str downcase)
-    $"($base_args) --composefs-backend --bootloader=($bootloader) --filesystem ext4 ./disk.img"
+    let boot_type = ($st.status.booted.composefs.bootType | str downcase)
+    # For UKI images, don't pass --bootloader as UKI boot setup handles it differently
+    if $boot_type == "uki" {
+        $"($base_args) --composefs-backend --filesystem ext4 ./disk.img"
+    } else {
+        let bootloader = ($st.status.booted.composefs.bootloader | str downcase)
+        $"($base_args) --composefs-backend --bootloader=($bootloader) --filesystem ext4 ./disk.img"
+    }
 } else {
     $"($base_args) --filesystem xfs ./disk.img"
 }