Set platform in RB backend

[alecandido]

This is a rough patch for the problem found in qiboteam/qibolab_platforms_qrc#151 (comment)

A better solution is postponed to a different version of Qibolab/Qibocal.

[andrea-pasquale]

Thanks @alecandido, it works for me.
Btw, there are other protocols which are using GlobalBackend. I can push directly here the changes or open a new PR adding the same modification for those protocols.

[alecandido]

Btw, there are other protocols which are using GlobalBackend. I can push directly here the changes or open a new PR adding the same modification for those protocols.

@andrea-pasquale feel free to push changes, if you wish.
The scope is meaningful, and the PR is definitely not big already.

[andrea-pasquale]

Btw, there are other protocols which are using GlobalBackend. I can push directly here the changes or open a new PR adding the same modification for those protocols.

@andrea-pasquale feel free to push changes, if you wish. The scope is meaningful, and the PR is definitely not big already.

I've pushed the changes here #943

[alecandido]

I've pushed the changes here #943

Then I'm merging this (it's still in another PR, and it will be needed to make that work)