fix(test): use portable file mode checks in snap installer tests (#3670)

The snap installer tests added in #3656 checked the gateway config mode
with GNU stat -c, which BSD stat on macOS rejects, so mise run ci failed
locally on macOS. Check the mode with find -perm instead, which matches
the exact mode on both GNU and BSD systems.

Signed-off-by: Kris Hicks <khicks@nvidia.com>

Author: krishicks

tasks/scripts/test-install-sh.sh

@@ -371,7 +371,7 @@ if ! grep -Fq 'allow_unauthenticated_users = true' "$snap_config"; then
   echo "FAIL: Snap gateway config must permit the plaintext local CLI" >&2
   exit 1
 fi
-if [[ $(stat -c '%a' "$snap_config") != 600 ]]; then
+if [[ -z $(find "$snap_config" -perm 600) ]]; then
   echo "FAIL: Snap gateway config must be mode 0600" >&2
   exit 1
 fi

tasks/scripts/test-snap-install-hook.sh

@@ -24,7 +24,7 @@ EOF
 common="${work}/fresh"
 SNAP_COMMON="$common" "$hook"
 cmp -s "$expected" "$common/gateway.toml"
-if [[ $(stat -c '%a' "$common/gateway.toml") != 600 ]]; then
+if [[ -z $(find "$common/gateway.toml" -perm 600) ]]; then
   echo "FAIL: install hook config must be mode 0600" >&2
   exit 1
 fi