Tweaking oci image invocation

cmd/demo/BUILD.bazel

@@ -28,12 +28,7 @@ load("@rules_oci//oci:defs.bzl", "oci_image")
 
 oci_image(
     name = "image",
-    architecture = select({
+    base = "//:distroless_base",
-        "@platforms//cpu:arm64": "arm64",
+    entrypoint = ["/demo"],
-        "@platforms//cpu:x86_64": "amd64",
-    }),
-    base = ":distroless_base",
-    entrypoint = ["/app"],
-    os = "linux",
     tars = [":tar"],
 )