Temporarily revert cleaning the backtraces.

Because it removes a lot of useful information that we desperately
need to debug new issues. Later we'll either revert this commit or
introduce some flag to control if backtraces have to be cleaned or
not.

Change-Id: Ie81f951c53a3c4647ae2fe1ac297feec1955f252
Reviewed-on: http://review.couchbase.org/33059
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>