refactor: cleanup preloader

[maiieul]

What is it?

• Feature / enhancement
• Bug
• Docs / tests / types / typos
• Infra

Description

Removing deprecated APIs as well as unnecessary ones. Cleaning up old logic to reduce code size and make it easier to inline the preloader logic in a future refactor.

Checklist

• My code follows the developer guidelines of this project
• I performed a self-review of my own code
• I added a changeset with pnpm change
• I made corresponding changes to the Qwik docs
• I added new tests to cover the fix / functionality

[changeset-bot]

🦋 Changeset detected

Latest commit: d268e21

The changes in this PR will be included in the next version bump.

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commit: 0ab8b68