treewide: use architecture-specific UEFI boot path

The default UEFI boot path depends on the architecture. This change is
needed for aarch64 support.

Change-Id: I69916ac5063e963b67ecdcdd814b0678c61da9fb
Reviewed-on: https://review.monogon.dev/c/monogon/+/4195
Reviewed-by: Tim Windelschmidt <tim@monogon.tech>
Tested-by: Jenkins CI
diff --git a/metropolis/installer/main.go b/metropolis/installer/main.go
index baf9cc8..20a8240 100644
--- a/metropolis/installer/main.go
+++ b/metropolis/installer/main.go
@@ -186,6 +186,7 @@
 			// whenever it's writing to block devices, such as now.
 			Data: 128,
 		},
+		Architecture:   osImage.Config.ProductInfo.Architecture(),
 		SystemImage:    systemImage,
 		EFIPayload:     efiPayload,
 		ABLoader:       structfs.Bytes(abloader),