Don't change behavior of SysV init scripts using "set -e" or "set -u"

Don't change behavior of SysV init scripts using "set -e" or "set -u"

/lib/lsb/init-functions.d/40-systemd unconditionally uses "set +e; set
+u". This can change the behavior of init scripts that use "set -e"
and/or "set -u".

Change the systemd integration to not rely on "set +e" or "set +u" but
instead work correctly in all cases by catching all commands that might
fail.

Closes: #751472