fix: don't transform process.env. when build target is node

[alex8088]

Description

When build target is node, process.env. will be left as is without transformation. Currently, process.env.FOO will always be transformed as ({}).FOO, which is undesirable when running in node.

Additional context

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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[bluwy]

Can you clarify why node is set for build.target? The option is used to define browser compatibility only, and using node doesn't sound right.

[alex8088]

Can you clarify why node is set for build.target? The option is used to define browser compatibility only, and using node doesn't sound right.

When we are developing a node oriented library,we sometimes need to use process.env.

[benmccann]

Also proposed in #8843. #5577 seems like it may be targeting the same issue as well