osbase/build: replace label_keyed_string_dict with string_keyed_label_dict

Before bazel 7.4 the string_keyed_label_dict attribute type wasn't available. fsspec_core_impl was using a label_keyed_string_dict which is structurally wrong but there was no alternative for it. This replaces that usage.

Change-Id: I36c02c84e6aa2557cd2beb09c07d3ceca501553d
Reviewed-on: https://review.monogon.dev/c/monogon/+/3853
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
Tested-by: Jenkins CI
diff --git a/metropolis/test/nanoswitch/BUILD.bazel b/metropolis/test/nanoswitch/BUILD.bazel
index 8e246ba..1dbf267 100644
--- a/metropolis/test/nanoswitch/BUILD.bazel
+++ b/metropolis/test/nanoswitch/BUILD.bazel
@@ -35,10 +35,10 @@
 node_initramfs(
     name = "initramfs",
     files = {
-        ":nanoswitch": "/init",
+        "/init": ":nanoswitch",
 
         # CA Certificate bundle
-        "@cacerts//file": "/etc/ssl/cert.pem",
+        "/etc/ssl/cert.pem": "@cacerts//file",
     },
     fsspecs = [
         "//osbase/build:earlydev.fsspec",