check-examples-on-wasm CI job keeps timing out stochastically

[alice-i-cecile]

See https://github.com/bevyengine/bevy/actions/runs/13751916389/job/38453938574

This appears to occur effectively at random: retrying the same merge often passes.

This is important to check so I'd really like to not remove it, but at the same time the unreliability and delay is really frustrating when trying to make changes.

@mockersf suggested to me that this may be due to instance overprovisioning causing OOM.

[alice-i-cecile]

With the consent of @mockersf, I've removed check-examples-on-wasm from the required checks for now. This should still be fixed, but at least it won't block completely unrelated fixes in the meantime.