Loggers that implement BufSize() (e.g. awslogs) uses the method to
tell Copier about the maximum log line length. However loggerWithCache
and RingBuffer hide the method by wrapping loggers.
As a result, Copier uses its default 16KB limit which breaks log
lines > 16kB even the destinations can handle that.
This change implements BufSize() on loggerWithCache and RingBuffer to
make sure these logger wrappes don't hide the method on the underlying
loggers.
Fixes#41794.
Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com>
bb11365e96