Drop tests for shipped one-shot migrations (#10318)

Keep the migrations themselves for late-updaters. Drop the tests that only
exercised frozen file rewrites from 4.0.0, and keep live invariants,
privileged repairs, and the migrator.

test/shell.d/limine-defaults-test.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+set -euo pipefail
+
+source "$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)/base-test.sh"
+
+packaged_defaults="$ROOT/etc/limine-entry-tool.d/omarchy-defaults.conf"
+
+grep -Fq 'KERNEL_CMDLINE[default]+=" initramfs_async=0"' "$packaged_defaults" ||
+  fail "the packaged Limine defaults still unpack the initramfs synchronously"
+pass "packaged Limine defaults keep Plymouth alive at the LUKS prompt"