Excessive renderable tiles generated when terrain is activated

[kkokkojeong]

maplibre-gl-js version: v5.0.1

browser: Chromium

Steps to Trigger Behavior

1. http://localhost:9966/test/examples/3d-terrain.html#19.99/47.27574/11.3908601
2. covering_tiles.ts

        export function coveringTiles(transform: IReadonlyTransform, options: CoveringTilesOptions): OverscaledTileID[] {
           // ....
          console.log('coveringTiles', !!options.terrain, result.length, options.terrain);
          return result.sort((a, b) => a.distanceSq - b.distanceSq).map(a => a.tileID);
        } 

3. Too many tiles are returned.
   
   

---

If you look at the screen above, there are very few tiles drawn on it.

When the terrain is deactivated, the number of covering tiles with a raster source is 2.
However, after enabling the terrain, the number of covering tiles (RenderToTexture) increases significantly to about 20.

This results in many renderable tiles being generated, causing the device to consume a large amount of GPU texture memory and triggering unnecessary draw calls.

I hope this issue can be improved. :)

[HarelM]

Cc: @NathanMOlson
Can you take a look at this?