Disable frame limiter setting on macOS/metal (where it isn't useful)

[peppy]

Discussed in #30396

^{Originally posted by brokenparts October 23, 2024}
Hi. Since the Metal renderer is always synced to the display refresh rate, I am suggesting that the frame limiter option be disabled when this backend is selected. Right now it just ignores whatever the user has set. This is confusing and looks like a bug without any explanation.

If visually disabling the dropdown doesn't make sense, maybe some explanatory text could be added.

False-positive reports: #24024 #25985 #30220 #30302

[shiumano]

In addition, Android's FPS is also forced by the display refresh rate. Unlike other platforms, though, there is nothing but OpenGL.