Memory leak on macOS with Metal rendering

[ltetak]

Describe the bug

There is a slow memory leak on macOS with metal rendering (does not repro on OpenGL or Software).

To Reproduce

Do anything that requires rendering but to speed things up drag a corner of the window and resize it a lot. This will gain 10MB/s. This memory is never freed up and climbs until the app eventually crashes (after a long time).
You can see this memory in the Activity Monitor under the Memory column. It's not calculated under Real Mem. I can't see it in dotMemory as well (is it a GPU memory?)

Expected behavior

Steady memory as with OpenGL or Software rendering.

Avalonia version

11.x - 11.2.0-beta2

OS

macOS

Additional context

It is more prominent since the Metal is the default renderer now #15994