log.decorate: only ignore it under "log --pretty=raw"

log.decorate: only ignore it under "log --pretty=raw"

Unlike notes that are often multi-line and disrupting to be placed in many
output formats, a decoration is designed to be a small token that can be
tacked after an existing line of the output where a commit object name sits.
Disabling log.decorate for something like "log --oneline" would defeat the
purpose of the configuration.

We _might_ want to change it further in the future to force scripts that
do not want to be broken by random end user configurations to explicitly
say "log --no-decorate", but that would be an incompatible change that
needs the usual multi-release-cycle deprecation process.

Signed-off-by: Junio C Hamano <gitster@pobox.com>