Update/refine gNB MAC stats, update L1

Only applicable with -q option.

Print a number of statistics, e.g., rx_ulsch_sdu to track UL MAC stats timing. Remove unused time_meas_t definitions, and fix the name for the total gNB scheduler time.

Print the RU stats in nrL1_stats.log, as some are already there, and do not "pollute" the periodic logs when -q is enabled.

I used this to see why there are sometimes late slots with Aerial. I used the above stats to get a general overview. This additional patch shows that at least in RFsim, the RLC indication in rx ulsch sdu can take up to 20us on my machine. Given that we can have multiple PDUs in UL (10?), this can amount to a sizeable amount of time. While this is for another MR, I thought the cleanup would be nice to have.