upstream: Use the operating system default DSCP marking for

upstream: Use the operating system default DSCP marking for

non-interactive traffic

It seems the CS1 traffic class mark is considered ambiguous and therefore
somewhat unhelpful (see RFC 8622 for more considerations). But, the new
'LE' scavenger class (also proposed in RFC 8622) offers high probability
of excessive delays & high packet loss, which would be inappropriate
for use with, for example, X11 forwardings. In fact, it is not known to
SSH what's appropriate because SSH is not aware of the content of what
passing through session forwardings. Therefore, no marking is appropriate.
Non-interactive traffic simply is best effort.

OK djm@ deraadt@

OpenBSD-Commit-ID: db1da1a432ecd53fc28feb84287aedb6bec80b01