If we ran out of net_buf's while sending, ignore the issue
and try to finish the test instead. Solving the "running out
of network buffers" case would require careful tuning of
number of network buffers, buffer size, upload speed etc. which
is difficult to solve with generic buffer count options.
The user should tweak mainly the CONFIG_NET_BUF_TX_COUNT option.
Optionally CONFIG_NET_PKT_TX_COUNT can be changed too. Information
about these options is printed to console after the test is finished.
Fixes#20315
Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>