Rebootstrap pipeline should update dotnet sdk version in `src/arcade/global.json`

[ellahathaway]

src/arcade/global.json must use the same dotnet sdk version as the root global.json

cc @ViktorHofer

[ViktorHofer]

This is currently needed as we flow the Arcade SDK entry out of the VMR. We might be changing this in the future so I would wait with any action.

[ViktorHofer]

dotnet/arcade-services#4847

[ellahathaway]

Closing as a duplicate