don't run create_surfaces system if not needed

[mockersf]

Objective

• Change set of systems as I made a mistake in Allow prepare_windows to run off main thread on all platforms #11672
• Don't block main when not needed
• Fixes Button example is broken #11235

Solution

• add a run condition so that the system won't run and block main if not needed

[BorisBoutillier]

I have checked that the create_surfaces system is effectively only run once at the beginning, so will not blocked the rendering even in Reactive mode after initial setup.

[hymm]

Ah cool. I didn't realize that not running prepare_windows on the main thread would help with reactive low power mode + pipelined rendering. Makes sense to me after I thought abo ut it for a bit. The render thread is being told to run the last time, but is being blocked because it wants to run prepare windows on the main thread, but the main thread is asleep. We should be careful about this in the move NonSend resources PR.

[mockersf]

Ah cool. I didn't realize that not running prepare_windows on the main thread would help with reactive low power mode + pipelined rendering. Makes sense to me after I thought abo ut it for a bit.

Yup it's a good surprise!