Borders example is broken on some machines

## Bevy version

main: commit 956d9ccbb1e6b240f3e434acaab9ad544df41102

## Relevant system information

```
AdapterInfo { name: "Intel(R) UHD Graphics 620 (KBL GT2)", vendor: 32902, device: 22807, device_type: IntegratedGpu, driver: "Intel open-source Mesa driver", driver_info: "Mesa 24.1.6-arch1.1", backend: Vulkan }
```

## What you did

```
cargo run --example borders
```

## What went wrong

It's supposed to look like this:

But the rounded borders flicker out of existence immediately after loading:

## Additional information

I have a strong suspicion that this has to do with https://github.com/bevyengine/bevy/pull/15163, which was merged 5 days ago, so I'm pinging @ickshonpe. The fact that it's very briefly visible also makes me think that this might be a `TemporaryRenderEntity` while it is supposed to persist. I'm not sure however as I believe I've tested this before merging #15320, and it was also broken.

Actually I'm 90% sure that it's a `TemporaryRenderEntity` while it isn't supposed to be.

Start by running `cargo run --example borders` at commit 956d9ccbb1e6b240f3e434acaab9ad544df41102 and compare the result with the expected image. Trace the rounded-border entities and the `TemporaryRenderEntity` behavior mentioned in the report, then verify that the borders remain visible after loading on the reported Vulkan/Mesa system.

Written by the indexing model from the issue text.