standalone mode java opts -Dnacos.standalone=true not work

[pnboot]

Issue Description

bug report

Describe what happened (or what feature you want)

standalone mode java opts -Dnacos.standalone=true not work

Describe what you expected to happen

a problem maybe in this code. i will fix it.
https://github.com/alibaba/nacos/blob/develop/core/src/main/java/com/alibaba/nacos/core/utils/SystemUtils.java

public static boolean STANDALONE_MODE = Boolean.getBoolean(STANDALONE_MODE_PROPERTY_NAME);

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[nkorange]

I think the original code is correct. So did you really encounter this error?

[pnboot]

I think the original code is correct. So did you really encounter this error?

sorry , set VM options , not Environment variables