Add aggregate specific metrics #23570

Is your feature request related to a problem or challenge?

Yes, running a query that takes a long time in the aggregator, you don't know what is taking the time there, which expression for example or what inside the expression

in our case we have aggregate with 2 aggregate expression that are the same (just on different column), in that aggregate expression impl there are multiple phases that can contribute to the timing

Describe the solution you'd like

having metrics per aggregate expression with the aggregate specific metric that can be declared will make it easier for visibility

Describe alternatives you've considered

No response

Additional context

No response