tests: Skip multi-device ESP test on non-UEFI systems

The multi-device ESP test creates ESP partitions and expects bootupd to
install a UEFI bootloader. On BIOS-booted systems, bootupd instead tries
to install GRUB for i386-pc, which requires a BIOS Boot Partition and
fails.

The test plan already requests UEFI provisioning via the hardware hint,
but Testing Farm does not always honor this on CentOS Stream x86_64.
Add a runtime check for /sys/firmware/efi so the test skips gracefully
on BIOS hosts rather than failing.

Assisted-by: Claude Code (Opus 4.6)
Signed-off-by: ckyrouac <ckyrouac@redhat.com>
Signed-off-by: Colin Walters <walters@verbum.org>

Author: ckyrouac

tmt/tests/booted/test-multi-device-esp.nu

@@ -420,6 +420,16 @@ def test_no_esp_failure [] {
 }
 
 def main [] {
+    # This test requires a UEFI-booted host because it creates ESP partitions
+    # and expects bootupd to install a UEFI bootloader.  On BIOS systems,
+    # bootupd would try to install GRUB for i386-pc which needs a BIOS Boot
+    # Partition instead of an ESP.
+    if not ("/sys/firmware/efi" | path exists) {
+        print "SKIP: multi-device ESP test requires UEFI boot"
+        tap ok
+        return
+    }
+
     # This test exercises bootupd-based bootloader installation which only
     # supports GRUB today.  Skip when the image uses systemd-boot.
     if (tap is_composefs) {