Remove @load for queries inside a +page.svelte

[SeppahBaws]

Currently it is possible to have a query marked with @load in a +page.svelte file.
Houdini will pick this up and server-side load this automatically for you, as if you put it in a +page.gql.

This has worked fine, but it is outdated and stems from a time before we had +page.gql.
Removing this code should also help clean up the codebase a bit.