Revert "weston: Use systemd notify,"

Commit 4efdcc10 ("weston: Use systemd notify,") has non-trivial to
backport dependencies without which it cannot work, revert backport.

In oe-core dunfell, weston is still started using /usr/bin/weston-start
script in meta/recipes-graphics/wayland/weston-init/weston@.service .
Since 76ed5342 ("weston-init: Use weston-launch when starting weston
as the first windowing system"), the weston-start script starts weston
using weston-launch executable in case $DISPLAY is not set, i.e. when
weston is started as the primary compositor.

When weston is started via weston-launch, the notification to systemd
is not delivered, and weston service fails to start with the following:
"
weston@root.service: start operation timed out. Terminating.
"

The weston systemd service has been reworked considerably since oe-core
dunfell in commit c21fa5a2 ("weston-init: Redefine weston service and
add socket activation option"), which replaced the use of weston-start
in weston@.service with plain weston, and has been further improved in
commit dd83fb40 ("weston-init: Stop running weston as root") . The
commit reverted here, oe-core/master commit c8aa0222 ("weston: wrapper
for weston modules argument"), landed only with the two aforementioned
reworks already in place, therefore the commit could have never been
tested with weston started via weston-launch executable and the timeout
at delivering systemd notification could not have happened in master.

Both c21fa5a2 ("weston-init: Redefine weston service and add socket
activation option") and dd83fb40 ("weston-init: Stop running weston
as root") are large feature patches and thus unsuitable for stable
backports, hence this revert seems to be the least problematic way.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Joshua Watt <JPEWhacker@gmail.com>
Cc: Pavel Zhukov <pavel.zhukov@huawei.com>
Cc: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>