Fix Promote Transaction issue

Author: cheenamalhotra

src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SqlDelegatedTransaction.cs

@@ -413,6 +413,8 @@ internal void TransactionEnded(Transaction transaction)
                         _active = false;
                         _connection = null;
                     }
+                    // Safest approach is to doom this connection, whose transaction has been aborted externally.
+                    connection.DoomThisConnection();
                 }
             }
         }

src/Microsoft.Data.SqlClient/netfx/src/Microsoft/Data/SqlClient/SqlDelegatedTransaction.cs

@@ -504,6 +504,8 @@ internal void TransactionEnded(SysTx.Transaction transaction)
                         _active = false;
                         _connection = null;
                     }
+                    // Safest approach is to doom this connection, whose transaction has been aborted externally.
+                    connection.DoomThisConnection();
                 }
             }
         }