Since we don't add a vtxConflicted vector to BlockConnected the
conflictedTxs member of PerBlockConnectTrace is no longer used.
This is a backport of Core PR17477 [3/6]
https://github.com/bitcoin/bitcoin/pull/17477/commits/5613f9842b4000fed088b8cf7b99674c328d15e1
Depends on D8865