[inventory] fix SC2015 for CI shellcheck 0.9

Unambiguous if-form for the two-condition guard. CI (node:20-bookworm,
Debian shellcheck 0.9) flags the A && B || C pattern where the koalaman
stable docker path passed. No behavior change.

CI evidence: https://git.knownelement.com/KNEL/inventory/actions/runs/118227
Ticket: https://projects.knownelement.com/issues/784

scripts/populate-netequip-from-librenms.sh

@@ -81,7 +81,9 @@ while IFS=$'\t' read -r fa pa fb pb; do
     [ -n "$fa" ] || continue
     pa=${pa:-unknown}; pb=${pb:-unknown}
     ida=$(ensure_port "$fa" "$pa"); idb=$(ensure_port "$fb" "$pb")
-    [ -n "$ida" ] && [ -n "$idb" ] || { echo "SKIP link $fa/$pa <-> $fb/$pb (missing CI/port)" >&2; continue; }
+    if [ -z "$ida" ] || [ -z "$idb" ]; then
+      echo "SKIP link $fa/$pa <-> $fb/$pb (missing CI/port)" >&2; continue
+    fi
     lo=$(( ida < idb ? ida : idb )); hi=$(( ida < idb ? idb : ida ))
     if api GET "search/NetworkPort_NetworkPort?criteria%5B0%5D%5Bfield%5D=13&criteria%5B0%5D%5Bsearchtype%5D=equals&criteria%5B0%5D%5Bvalue%5D=$lo" \
         | grep -q "\"$hi\""; then conn_dup=$((conn_dup+1)); continue; fi