trim the beam_ off the beginnings of job names

[kennknowles]

Just a nit that drives my brain nuts. Also it scrolls more characters off the end of the job name so makes GitHub UI annoying.

Methodology:

• search and replace beam_([A-Z]) and replace with $1
• `rename -s beam_ '' * .github/workflows/*

The chance that this breaks something random where someone regexed against the job name is pretty high, though the global search shows nothing remains. But of course some bits won't use the repo as the source of truth. And probably some grafana queries need to be old job name OR new job name, etc, etc. And probably some ill-advised fragile uses that I miss in the above obvious stuff.

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