replicate_random() should support same region

[ShishirPatil]

Given the current evolution of skyplane, we should make replicate_random between src==dest to move data between 2 machines within the same region.

https://github.com/skyplane-project/skyplane/blob/b5e06b7cac1a1d6c737d448666666d805316608b/skyplane/cli/cli_internal.py#L39

[parasj]

Why would this make sense? If we are in one region, Skyplane will only provision one side of the transfer VMs.

For A => B, Skyplane will provision two VMs: A:VM1 => B:VM2

For A => A, Skyplane will provision one VM: A:VM1 => A:VM1