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/installer/BUILD.bazel b/metropolis/installer/BUILD.bazel
index 61cf7b6..a2790b4 100644
--- a/metropolis/installer/BUILD.bazel
+++ b/metropolis/installer/BUILD.bazel
@@ -31,7 +31,7 @@
 node_initramfs(
     name = "initramfs",
     files = {
-        "//metropolis/installer": "/init",
+        "/init": "//metropolis/installer",
     },
     fsspecs = [
         "//osbase/build:earlydev.fsspec",