fix: show mined timestamp for import tx (#5012)

Description
---
Don't show the current time for an import, rather show the mined timestamp

Motivation and Context
---
Fixes: #4923

base_layer/wallet/src/transaction_service/storage/database.rs

@@ -669,7 +669,7 @@ where T: TransactionBackend + 'static
             ),
             TransactionStatus::try_from(import_status)?,
             message,
-            Utc::now().naive_utc(),
+            mined_timestamp.unwrap_or(Utc::now().naive_utc()),
             TransactionDirection::Inbound,
             maturity,
             current_height,