Fix GitLab reply in ThroughputProfileHandler

Do not use lhcbpr to query throughput result as this fails due to slow update of lhcbpr and then breaks gitlab reply in ThroughputProfileHandler.

I think that this MR technically leaves utils/lhcbpr.py unused but for now I want to introduce minimal changes needed to get the reply back into reliable shape.
Everything else can be revisited once @rmatev is back.

@maszyman could I ask you to have a quick look over this and then merge?