[lbry] blockchain: clear statusValid upon statusValidateFailed is set

The status management of index does need some refactoring.
For now, we just manually clear the statusValid in every occurance
of statusValidateFailed being set.

Co-authored-by: Roy Lee <roylee17@gmail.com>

blockchain/chain.go

@@ -1004,6 +1004,7 @@ func (b *BlockChain) reorganizeChain(detachNodes, attachNodes *list.List) error
 		err = b.checkConnectBlock(n, block, view, nil)
 		if err != nil {
 			if _, ok := err.(RuleError); ok {
+				b.index.UnsetStatusFlags(n, statusValid)
 				b.index.SetStatusFlags(n, statusValidateFailed)
 				for de := e.Next(); de != nil; de = de.Next() {
 					dn := de.Value.(*blockNode)
@@ -1141,6 +1142,7 @@ func (b *BlockChain) connectBestChain(node *blockNode, block *btcutil.Block, fla
 			if err == nil {
 				b.index.SetStatusFlags(node, statusValid)
 			} else if _, ok := err.(RuleError); ok {
+				b.index.UnsetStatusFlags(node, statusValid)
 				b.index.SetStatusFlags(node, statusValidateFailed)
 			} else {
 				return false, err
@@ -1175,6 +1177,7 @@ func (b *BlockChain) connectBestChain(node *blockNode, block *btcutil.Block, fla
 			// that status of the block as invalid and flush the
 			// index state to disk before returning with the error.
 			if _, ok := err.(RuleError); ok {
+				b.index.UnsetStatusFlags(node, statusValid)
 				b.index.SetStatusFlags(
 					node, statusValidateFailed,
 				)