channeldb: remove unused fwdPackageLogBucket key
channeldb: remove unused fwdPackageLogBucket key

In this commit, we move the declaration of the key for an unused bucket.
In the past, this bucket was used to store the revocation forwarding
package log. However, this has been moved under the key
`fwdPackagesKey`.

LightningNetwork/lnd,LightningNetwork/lnd,aakselrod/lnd,aakselrod/lnd