fix: flakiness in e2e funds transfer

Which occurred when the transaction created at Babbage era was submitted at Conway era.
The funds transfer is now considered valid as soon as at least one transaction has been submitted.

Author: jpraynaud

mithril-test-lab/mithril-devnet/mkfiles/mkfiles-mithril-payment.sh

@@ -153,8 +153,18 @@ cat >> payment-mithril.sh <<EOF
 # Run payment iterations
 for (( j=1; j<=\${PAYMENT_ITERATIONS}; j++ ))
 do
+    set +e
     process_payment_iteration \$j
+    set -e
 done
+
+# Check that at least one transaction has been successfully submitted
+TOTAL_TX_SUBMITTED=\$(cat ${TX_ID_OUTPUT_FILE} | wc -l)
+if [ \$TOTAL_TX_SUBMITTED -eq 0 ]; then
+    echo ">>>>>> Error: No transaction was successfully submitted!"
+    exit 1
+fi
+
 EOF
 
 chmod u+x payment-mithril.sh