With SDK 3.3.1 I do not get the <inf> logging messages when building the Hello World app unless CONFIG_LOG=y is added to prj.conf.
Perhaps this is left as an exercise for the reader!
Nordic AI says "Note that in nRF Connect SDK, CONFIG_LOG (along with CONFIG_LOG_MODE_MINIMAL) is automatically enabled for all samples via CONFIG_NCS_SAMPLES_DEFAULTS." but this doesn't seem to apply for the Hello World sample.