The aggregate option for stats command given wrong result

These is a $no_aggregate array for some variable which don't aggregate:

// Some variables don't logically aggregate.
$no_aggregate = [
  'pid',
  'time',
  'version',
  'libevent',
  'pointer_size',
  'accepting_conns',
  'listen_disabled_num',
];

However, the variable keys are not clearly known (actually it is from 0 to 42 I think) but even if we exclude from aggregation, it completely strips the variable from the result, it does not keep the first or last occurrence.

We would need to add some logic here to accept "regex" variable name and to keep the first or last occurrence.

I am actually wondering if there is any guarantee that 2 slabs with the same ID on different servers will always have the same chunk size. In other words, I am wondering if aggregating on keys makes any sense when talking about stats slabs. If we really want to aggregate slabs statistics from multiple servers, it has to be done on the chunk_size to be consistent.