shell: drop --wait
This flag is deprecated in Kubernetes 1.26 and removed in 1.29; according to Kubernetes commit 09804a198c it has no effect, at least as of Kubernetes 1.26 (it’s not entirely clear whether it ever had an effect or not).
Very recently, Kubernetes 1.31 apparently added a --wait flag to
kubectl run
again, but I very much doubt that Bryan foresaw this
and intended to refer to that flag when he added --wait=true in change
I8be6562acd (commit fd2d21a3) four years ago.
Bug: T373866