Deduplicate state transition metrics and separate by label

it's nice to move metric definition to state-transition but I'd like to add a label to this
when we run stateTransition from normal flow, pass in `BlockSource`
when we run from regen, pass in `regen`
when we run from historical state regen, pass in `historical_regen`

and deduplicate the same set of metrics there, then update dashboard with the label, that would make the work more valuable for us

_Originally posted by @twoeths in https://github.com/ChainSafe/lodestar/pull/7577#discussion_r2057288309_