[Refactor] Simplify control flow in abortSignalFromRequestBehaviour

[gonzaloriestra]

What changed?

Refactored abortSignalFromRequestBehaviour in packages/cli-kit/src/public/node/http.ts to replace mutable local variable assignment (let signal) and nested if / else if statements with linear guard clauses and early returns.

Why?

Simplifies control flow, improves code readability, and eliminates unnecessary variable reassignments without changing observable behavior.

How to test your changes?

CI

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PR created automatically by Jules for task 741939202906716487 started by @gonzaloriestra

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