WishlistIntake: remove 'exists' reactive state
This hasn't been needed in some time, since we always have an existing page when the intake form loads (for fallback text).
Related: T367917
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Support: mw:GitLab, how to host a project on GitLab, #wikimedia-gitlab on libera.chat, #GitLab on Phabricator.
This hasn't been needed in some time, since we always have an existing page when the intake form loads (for fallback text).
Related: T367917