In general, it's better to avoid a negation. And "!" is special, because it is
used for history expansion, i.e. the same command would behave differently if
pasted on the command line.
Inspired by 4a899c5a23.
(The one case that is left unchanged is '< <(subcommand)'.)
This way, the style with no gap was already dominant. This way, the reader
immediately knows that ' < ' is a comparison operator and ' << ' is a shift.
In a few cases, replace custom EOF replacement by just EOF. There is no point
in using someting like "_EOL" unless "EOF" appears in the text.
In 'udevadm lock' the device /dev/loopX is locked instead of
/dev/loopXp1. Hence, 'udevadm wait' should wait for /dev/loopX.
For some reasons, the kernel sometimes does not emit uevent for
partitions, and 'udevadm wait' for partitions may fail.
Fixes#24360.
It's hard to trigger the failure to exit the rate limit state in
isolation as it needs multiple event sources in order to show that it
gets stuck in the queue. Hence why this is an extended test.