linux-aurora: drop the generic linux provide and ship on edge only

The kernel provided linux=, so on any aarch64 root with the omarchy repo
listed before core, a dependency on linux resolved to this Apple-only kernel
instead of ALARM's linux-aarch64. linux-asahi and WIREGUARD-MODULE stay.

Channel membership narrows to edge until M1 and M2 cold-boot qualification;
promotion widens it again. pkgrel moves to 10 because 7.1.12.aurora2-9 is
already published and a filename is immutable.

pkgbuilds/linux-aurora/.omarchy/package.json

@@ -1,6 +1,5 @@
 {
   "source": "local",
   "skip_build": true,
-  "release_ring": "fast",
-  "channels": ["edge", "rc"]
+  "channels": ["edge"]
 }