Remove #[derive(Resource, Component)] from tests

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Objective

Multiple tests derive both Resource and Component on a single struct. In the current resources-for-components plan (#19731), this leads to a conflict.

Solution

#[derive(Resource, Component)]
struct A;

Becomes

#[derive(Component)]
struct A;

#[derive(Resource)]
struct ResA;

and the tests are changed accordingly.

There was one test that had to be removed as it specifically tested that a query could both query a resource and a component with the same name. That test doesn't make any sense anymore, so I removed it.

Testing

I tested the changes by adding code into Resource derive macro, that also derives Component, so any conflicts showed up by running cargo build.

Future work

AmbientLight in bevy_light still derives both, but since that requires a little more work, I'm saving it for later.