Minor issues with the new group prediction log messages with gc+ergo+cset:

* add group id to be able to refer to it more easily

* add total time

* shorten message a bit

* A "y" is missing at "bytes_to_cop" in the log message for group predictions with gc+ergo+cset=trace:

Prediction for group with 76 regions, card_rs_length 320, merge_scan_time 0.02ms, code_root_scan_time_ms 0.00ms, evac_time_ms 9.92ms, other_time 45.60ms, bytes_to_cop 61408560