portable: do not use SYNTHETIC_ERRNO for sd_bus_error_set_errno()

The concept of synthetic errnos is about logging, which
is irrelevant irt bus error and we don't do any special
treatment in sd-bus for them, meaning the value propagated
would be spurious.

(cherry picked from commit 2f2058d)
(cherry picked from commit 018c7fb)

Author: YHNdnzj

src/portable/portable.c

@@ -620,7 +620,7 @@ static int extract_image_and_extensions(
                 if (r < 0)
                         return r;
                 if (isempty(id))
-                        return sd_bus_error_set_errnof(error, SYNTHETIC_ERRNO(ESTALE), "Image %s os-release metadata lacks the ID field", name_or_path);
+                        return sd_bus_error_set_errnof(error, ESTALE, "Image %s os-release metadata lacks the ID field", name_or_path);
 
                 if (prefixes) {
                         valid_prefixes = strv_split(prefixes, WHITESPACE);
@@ -664,7 +664,7 @@ static int extract_image_and_extensions(
                                 r = extension_release_validate(ext->path, id, version_id, confext_level, "portable", extension_release, IMAGE_CONFEXT);
 
                         if (r == 0)
-                                return sd_bus_error_set_errnof(error, SYNTHETIC_ERRNO(ESTALE), "Image %s extension-release metadata does not match the root's", ext->path);
+                                return sd_bus_error_set_errnof(error, ESTALE, "Image %s extension-release metadata does not match the root's", ext->path);
                         if (r < 0)
                                 return sd_bus_error_set_errnof(error, r, "Failed to compare image %s extension-release metadata with the root's os-release: %m", ext->path);
                 }