* trigger re-establshemnt on DU: reset RLC counters on DRB 1
  for OAI UE, since SRB 1 does not work for lack of periodic
  measurements reports
* how is the re-establishment triggered?
  * a transmission on DRB 1 occurs
  * detection of a mismatch of RLC counters at the UE side
  * max number of RLC retransmissions reached
  * RLF detection
* verify re-establishment on CU: we ping the core from the UE; this
  sends packets on DRB, and because the sequence number mismatches, will
  trigger a reestablishment. We accept in the ping that a couple of
  packets might be lost; after ping is over, reestablishment must be
  done as well (else the ping will already fail).

If the RLC cannot retransmit a package, 3GPP specs say that we should
declare radio link failure (RLF). Up to this commit, the code did
nothing though. In this commit, add a per-UE RLF callback; the RLC will
call into this function to signal that RLF has been detected through
maximum retransmissions on a particular RLC bearer.

Integration: `2024.w45`

See merge request oai/openairinterface5g!3097

* !3048 Cleanup and refactoring at gNB initialization
* !3077 Address most thread safety issues in NR UE
* !3089 Improve cross-compile documentation
* !3092 Remove Interop-F1/Accelleran-CU testing pipeline
* !3096 Remove x86-specific instructions from telnet server
* !2949 Better polar decode
* !3070 CI: Add test with 4 DL layers, 60 MHz BW to SA-2x2 pipeline
* !3098 nr rlc: hotfix: test allocation valid before use
* !3090 Add UL PRBs Blacklist section to NR_SA_Tutorial_COTS_UE.md
* !3082 fix blocking bugs in command nr_dlsim -n100 -e27 -s35 -b 273 -R273 -x4 -y4 -z4
* !3100 CI: Remove 5g_l2sim files
* !3024 Set SA mode as default
* !3087 Remove some usage of the old CI sshConnection class
* !3074 CI: cleanup of cls_physim.py

CI: Cleanup of cls_physim.py

- Remove unused code and file
- Rework functions for CUDA and T2 log analysis
- Check if test was successful for nr_ulsim and nr_dlsim in
  RAN-gNB-N300-Timing-Phytest-LDPC pipeline

Remove some usage of the old CI sshConnection class

Set SA mode as default

- Set standalone (SA) mode as the default.
- Adjust commands in Docker Compose files by removing --sa flags and
  adding --nsa flags where applicable.
- Add a function to verify that only one mode is being used at a time.
- Update all relevant documentation.

Increase number of cores used for T2 nr_ulsim/nr_dlsim processing to ensure
a fair comparison of total gNB PHY RX/TX processing time.

CI: Remove 5g_l2sim files

Delete the XML, conf, and YAML files related to the RAN-L2-Sim-Test-5G pipeline
that has already been removed.

In the last commits, SSHconnection class has been removed from
cls_containerize.py. We therefore don't need the username and password,
as cls_cmd uses certificates only. Remove the usage of the username and
the password, and harmonize the use of GetCredentials().

Recent refactoring replaced the CreateWorkspace function call with a
dedicated XML step (for clarity, and because it avoids needless
recreation of workspaces). In the proxy function, the same
CreateWorkspace xml step has been added, cloning the OAI RAN repo, when
we actually need the repository for the proxy. Hence, fix this by
calling the CreateWorkspace() function manually, but only when
necessary, to build the proxy. (It would only be a problem if the
pipeline would rebuild the proxy, which did not happen because not much
work is happening on the proxy repo).

Further, refactoring and simplication of the proxy build function were
done:

- never tag proxy with develop, that makes no sense
- overwrite CreateWorkspace() info after having created and used the
  workspace (the "if" to build the proxy)
- simplify copying of logs
- add simple unit test
- remove check for ubuntu; the dependcy is "docker". Simplify the code
  to not obscure with a class variable.

The first thing Build_Proxy does is to remove the repository. Further,
Build_Proxy does not use the OAI RAN repo, but the proxy repo. The
Create_Workspace() is therefore completely useless.

Remove CheckAndAddRoute(), as it is complicated to read, uses a
multitude of hostname/IP/password combinations. Replace with scripts on
the machines, which, as of this commit, are:

- porcepix: ~/after-reboot.sh
- ofqot: ~/after-reboot.sh
- nepes: ~/after-reboot.sh
- obelix: ~/how-to-resetup-obelix-out-of-reboot.sh

It is clearer in CI logs to use absolute paths, and that is also a
"preference" of the new SSH class (cls_cmd.py) in the sense that some
functions don't handle "cd" gracefully (because of underlying Python
library paramiko).

For zip, though, we should change to have nice relative paths in the
archives, so use cd <path> && zip ... to achieve that, instead of
changing to a directory. This way, the path on which we operate is still
visible in the logs in each line.

The clang build fails with

    /oai-ran/openair1/PHY/MODULATION/gen_75KHz.cpp:16:23: error: variable length arrays in C++ are a Clang extension [-Werror,-Wvla-cxx-extension]
       16 |     complex<double> t[len];
          |                       ^~~
    /oai-ran/openair1/PHY/MODULATION/gen_75KHz.cpp:16:23: note: function parameter 'len' with unknown value cannot be used in a constant expression

So ignore this warning (and make the build pass), since OAI uses VLAs in
various places.

The previous version would put the user-defined options first. However,
the default options include e.g., -Wall. If a user tries to override
(see for instance the next commit) -Wall or other options might override
this and not honor the user choice.

To always have the user have the last work, put user-defined compile
options last.

THere are four possibilities, for the three options (phy_test, do_ra,
nsa):

- None is set -> SA
- Only one is set of each -> corresponding mode

Introduce a function softmodem_verify_mode() to check for these.