In phy-test, the scheduler has a hardcoded UE allocation; if CQI and RSRP
are not evaluated, there is no change in the scheduler function. Also,
this avoids misleading error messages if no UE is connected.

Co-authored-by: Robert Schmidt <robert.schmidt@openairinterface.org>

improvements in Bj computation and implementing a timer to compute time elapsed since last Bj update

- The DL MCS adapted based on the BLER for the minimum number of
DL(numd_sched) grants for the UE in the pre_configured number of frames.
The current threshold value is set to be >9 for 16 UE capacity.
- With increased number of UE to 32 and when all the UEs are DL data active
the num_dl_sched is not meeting the threshold value. Due to whcih the MCS
of all the UEs are stuck with MCS 10-12 in good channel condition.
- The threshold value is adjusted to support 32 UE capacity increase.

 - Added the limit as MAX_DCI_CORESET for max_sched_ues in DL/UL scheduler.
This is needed because gNB crashes when tested with 100MHz cell as the
scheduler tries to schedule 11 UEs in a slot and the DCI informaiton is
corrupted due to the limitation in NFAPI interface because of
MAX_DCI_CORESET size.

The memory allocation is increased to enable the periodic mac stats logging
to enable increased number of UEs data.

Use the correct function in order to close open RFsim connections,
instead of a simple close(). If this is not done correctly, it might
happen that the softmodem closes, but an L1 thread might still read
samples (bug in higher layers). Then, RFsim tries to read a socket
(because it has an open connection), but the actual connection had been
close()d. This commit fixes this behavior.