SAR-149 Ensure message logged only when new transaction ID is generated.

src/ska/logging/transactions.py

@@ -76,7 +76,6 @@ class Transaction:
 
         if not self._transaction_id:
             self._transaction_id = self._get_from_params_or_generate_new_id()
-            self.logger.info(f"Generated transaction ID {self._transaction_id}")
 
         if transaction_id and params.get(self._transaction_id_key):
             self.logger.info(
@@ -113,6 +112,7 @@ class Transaction:
         transaction_id = self._params.get(self._transaction_id_key)
         if not self._is_valid_id(transaction_id):
             transaction_id = self._generate_new_id()
+            self.logger.info(f"Generated transaction ID {transaction_id}")
         return transaction_id
 
     def _is_valid_id(self, transaction_id):