chore: fix shellcheck findings across migration scripts

phase3_runners.sh

@@ -30,7 +30,7 @@ if [[ ! -f "$RUNNERS_CONF" ]]; then
 fi
 
 # Count non-comment, non-blank lines to verify there are runners to deploy
-RUNNER_COUNT=$(grep -v '^\s*#' "$RUNNERS_CONF" | grep -v '^\s*$' | wc -l | xargs)
+RUNNER_COUNT=$(grep -Evc '^[[:space:]]*($|#)' "$RUNNERS_CONF")
 if [[ "$RUNNER_COUNT" -eq 0 ]]; then
   log_error "No runners defined in runners.conf"
   exit 1