[CLI] Emit correct row count from CLI sql subcommand JSON mode

[pcholakov]

Trivial little fix for something that caught my eye.

Before:

❯ restate sql "select value_utf8 from state limit 1" --jsonl
{"value_utf8":"{\"userId\":\"usr_101\",\"accounts\":[{\"accountId\":\"acc_10uhnxdeyrnKSVnXhgWouLo\",\"name\":\"updated-name\"}]}"}
0 rows. Query took 8.624792ms

After:

❯ ./target/debug/restate sql "select value_utf8 from state limit 1" --jsonl
{"value_utf8":"{\"accountId\":\"acc_10uhnxddRv3UE4UbJiWqbmi\",\"primaryOwnerUserId\":\"usr_101\",\"environments\":[],\"name\":\"integration-test-account-01j1sw6fqw8tcsn20jmeyrfx3g\"}"}
1 rows. Query took 9.157292ms