[chore](macOS) Fix JAVA_OPTS in start_be.sh (apache#19267)

We should set -XX:-MaxFDLimit on macOS if we enable java support for BE otherwise BE may fail to start up.

bin/start_be.sh

@@ -287,7 +287,15 @@ else
 fi
 
 if [[ "${MACHINE_OS}" == "Darwin" ]]; then
-    final_java_opt="${final_java_opt} -XX:-MaxFDLimit"
+    max_fd_limit='-XX:-MaxFDLimit'
+
+    if ! echo "${final_java_opt}" | grep "${max_fd_limit/-/\-}" >/dev/null; then
+        final_java_opt="${final_java_opt} ${max_fd_limit}"
+    fi
+
+    if [[ -n "${JAVA_OPTS}" ]] && ! echo "${JAVA_OPTS}" | grep "${max_fd_limit/-/\-}" >/dev/null; then
+        JAVA_OPTS="${JAVA_OPTS} ${max_fd_limit}"
+    fi
 fi
 
 # set LIBHDFS_OPTS for hadoop libhdfs