Drop setuid from chrome-sandbox and keep Obsidian's tests in its package

Chromium sandboxes through unprivileged user namespaces on Arch-family
kernels, so the setuid-root helper is unnecessary. The watcher tests now run
from check() as checksummed package sources, leaving tests/ and the shared
Tests workflow untouched.

pkgbuilds/obsidian/.omarchy/upstream.sh

@@ -1,3 +1,3 @@
 #!/bin/bash
 set -euo pipefail
-python3 "$(dirname "$0")/upstream.py"
+python3 "$(dirname "$0")/../upstream.py"