What

Export two metrics from the KVS for shards.

Why

We noticed a memory leak in the KVS. Those metrics can be used to check whether the leak is still happening or not.

How

Export the size of the table as metrics.

Manually testing the MR

dune exec tezt/tests/cloud/main.exe -- cloud dal -v --log-file /tmp/log --stake 1,2,3,4 --prometheus --localhost

and check the value of those metrics. Currently we should observe a leak for the opened_files metrics on the bootstrap node at least.