XDCR - CCR in error scenario may print invalid error msg

https://github.com/couchbase/goxdcr/blob/master/parts/xmem_nozzle.go#L2706-L2708

There is a chance that the Body is snappy compressed, and the sizes may not be parsed correctly.

Also, perhaps better to just print the Key instead of the body... since a non-hex dump of the body will show up unusable anyway... something like:

[12 33 55 6 3 11 22 ...]