fix(spec): Fix duplicate definitions

[pierwill]

Rename some rules for the builtin statement to avoid ambiguity.

Closes #5186.

Checklist

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• ✏️ Write a PR description, regardless of triviality, to include the value of this PR
• 🔗 Reference related issues
• 🏃 Test cases are included to exercise the new code
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  No feature changes, but this does update the specification.

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[pierwill]

Does this need changes in source code as well?

[nathanielc]

Does this need changes in source code as well?

It does not, the source code will already have used unique function names for the production rules.