samples: telnet: net shell is not working

[tedd-an]

Describe the bug
Found couple of issues:
log_strdup_alloc_failed error
net shell is not working from the telnet side even if the connection is established

To Reproduce
Steps to reproduce the behavior:

1. samples/net/telnet
2. mkdir build; cd build
3. cmake -GNinja -DBOARD=qemu_x86 ..
4. ninja && ninja run
5. From the terminal,
   $ telnet 192.0.2.1

Expected behavior
Access net shell via telnet

Impact
Sample is not working as described in https://docs.zephyrproject.org/latest/samples/net/telnet/README.html

Screenshots or console output
output attached
telnet-output.txt

Environment (please complete the following information):

• OS: Linux FC28
• Toolchain Zephyr SDK
• 3dea408

[tedd-an]

it looks like similar issue #12611

[jukkar]

Yes, the telnet cannot be used atm as the shell is missing support for network transport.

[jukkar]

Duplicate of #12611