w: invalid truncating with long usernames

With a long username, the username isn't truncated and breaks the test "test_output_format". upstream w: ``` USER TTY LOGIN@ IDLE JCPU PCPU WHAT taxrosde tty3 03Jun25 9days 0.03s 0.03s /usr/bin/startplasma-wayland ``` our w: ``` USER TTY LOGIN@ IDLE JCPU PCPU WHAT taxrosdevtty3 Tue03 9days 0.03 0.03 /usr/bin/startplasma-wayland ``` The question is whether we truncate it (upstream behaviour), or whether we move the headers along and don't have to truncate anything. If we do go against upstreams behaviour, theres a very low chance of breaking scripts as they likely expect the username to be small in the first place and split by spaces.