Improve performance of `wp user list --format=count`
Improve performance of `wp user list --format=count`

* Only fetch user IDs, to avoid join with user meta table.
* Skip unnecessary `SQL_CALC_FOUND_ROWS`

gedex/wp-cli,shawnhooper/wp-cli,rodrigoprimo/wp-cli,aaemnnosttv/wp-cli,miya0001/wp-cli,2ndkauboy/wp-cli,gitlost/wp-cli,trepmal/wp-cli,shawnhooper/wp-cli,nyordanov/wp-cli,rodrigoprimo/wp-cli,miya0001/wp-cli,GaryJones/wp-cli,nyordanov/wp-cli,gedex/wp-cli,gedex/wp-cli,gitlost/wp-cli,trepmal/wp-cli,GaryJones/wp-cli,rodrigoprimo/wp-cli,nyordanov/wp-cli,aaemnnosttv/wp-cli,trepmal/wp-cli,miya0001/wp-cli,2ndkauboy/wp-cli,shawnhooper/wp-cli,2ndkauboy/wp-cli,gitlost/wp-cli,aaemnnosttv/wp-cli,GaryJones/wp-cli