Remove warnings about "queue only" default being swapped to "wait"

A couple of months ago, we changed the CLI's defaults so that, when migrating a repo, we wait for the migration to finish by default, rather than just queueing it and then exiting.

Having given some warnings to users, we should now remove this:

https://github.com/github/gh-gei/blob/main/src/gei/Commands/MigrateRepo/MigrateRepoCommandArgs.cs#L61
https://github.com/github/gh-gei/blob/5bdf071564e35eaff223d8c8ad525e7c176cdd3a/src/bbs2gh/Commands/MigrateRepo/MigrateRepoCommandArgs.cs#L109
https://github.com/github/gh-gei/blob/5bdf071564e35eaff223d8c8ad525e7c176cdd3a/src/ado2gh/Commands/MigrateRepo/MigrateRepoCommandArgs.cs#L36

## Todo

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## Dependencies

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