[backport#16624 2/4] Remove SyncTransaction for conflicted txn in CWallet::BlockConnected

Summary:
We shouldn't rely on this sync call to get an accurate view of txn
state, if a tx conflicts with one in mapTx we are going to update
our wallet dependencies in AddToWalletIfInvolvingMe while conflicting
txn get connected. If it doesn't conflict with one of our dependencies
we are not going to track it anyway.

This is a cleanup, as this SyncTransaction is redundant with the
following one for confirmation which is triggering the MarkConflicted
logic. We keep the loop because set of conflicted txn isn't same as txn
included in block.

https://github.com/bitcoin/bitcoin/pull/16624/commits/7e89994133725125dddbfa8d45484e3b9ed51c6e

Depends on D7048

Partial backport of Core PR16624

Test Plan:

ninja check check-functional

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D7049