only create admin account the first time

when importing an external traccar with on admin, this ends up
creating an admin

start.sh

@@ -28,7 +28,7 @@ ensure_admin_account() {
     wait_for_table tc_users;
 
     echo "==> Ensure admin account"
-    count=`$mysql --skip-column-names -s -e "SELECT COUNT(*) FROM tc_users WHERE name='admin';"`
+    count=`$mysql --skip-column-names -s -e "SELECT COUNT(*) FROM tc_users;"`
     if [[ "$count" = "0" ]]; then
         echo "==> Create initial admin account"
         # Values are from https://github.com/traccar/traccar/blob/master/schema/changelog-3.3.xml#L179 which is not used anymore, but we still want the admin account