Outlier Detection gRFC

[Sotiris Nanopoulos]

Hello,

We are adopting outlier detection at my workplace and our initial approach as we were tuning the knobs in protocol was to set `enforcing_success_rate` to `0` and observe the system via `channelz` + metrics to determine if the values we chose are correct.

After quite some digging into why `outlier detection` was no triggering we realized that `enforcing_success_rate` set to `0` disables the feature with a no-op config instead of putting the feature in shadow mode.

So I wanted to send this message to understand better  what the original motivation for this was and if other people have faced a similar issue/discuss if this is the behaviour we want in the future.

Thanks,
Sotiris