`Start native repl` always opens repl to side even if there is nothing open

[mjbvz]

Testing #23994

1. Close all open editors

2. Run Start native python repl

Bug
The repl still opens to the side of the empty editor

It's consistent but also seems kind of unexpected

[anthonykim1]

Yeah, we should probably just open it on the "main" view if there arent any tabs opened. Thanks for this.