[cleanup] remove redundant code after merge from cross-shard

Signed-off-by: Leo Chen <leo@harmony.one>

cmd/harmony/main.go

@@ -169,9 +169,6 @@ func initSetup() {
 }
 
 func passphraseForBls() {
-	if *isExplorer {
-		return
-	}
 	// If FN node running, they should either specify blsPrivateKey or the file with passphrase
 	if *isExplorer {
 		return