Subnautica: don't override plando during pre_fill

[Berserker66]

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Please format your title with what portion of the project this pull request is targeting and what it's changing.

ex. "MyGame4: implement new game" or "Docs: add new guide for customizing MyGame3"

What is this fixing or adding?

potential conflict with plando placing items into Subnautica sphere 1

How was this tested?

not, I have trust

If this makes graphical changes, please attach screenshots.