Tiles continuously load/unload outside camera frustrum when pitched

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**mapbox-gl-js version**: latest

### Question

When the camera is pitched beyond ~45 degrees and you orbit the camera, you end up with an almost-constant unloading & loading of the same tiles. It seems like the system is fairly aggressive in removing tiles that are out of view. For a top-down slippy map that makes sense, but in the case of the 3D map with rotation & pitch, it's extremely likely that nearby tiles behind the camera will be seen again. This pruning results in tiles near the camera being unloaded/reloaded a lot.

In a system where the camera is rotating frequently, for example following a moving object, this produces a lot of unnecessary / duplicative network requests and janky map behavior.

Is it possible somehow to configure the system to be keep more tiles in memory, for example to keep all tiles nearby the camera in memory even if they are out of view?

_Steps to reproduce_:
- Load a mapbox scene with 3D terrain
- Configure to allow rotation/pitch
- With the camera pitched to >45deg, rotate in increments of >=90deg.
- Observe that the area outside the camera frustrum keeps unloading.

### Links to related documentation

No source file or test is named in the issue. Start by reproducing the behavior with pitched terrain and repeated camera rotation, then trace the tile visibility and unloading path. Done means establishing whether nearby out-of-view tiles can be retained without excessive memory or requests, with regression coverage for the reported camera movement.

Written by the indexing model from the issue text.