Hello,
I'm not sure I get what exactly you want to achieve. Is it: "If any test no matter what cluster it is on exceeds threshold for more than 10 minutes then trigger an alert."?
In this case you can just remove "name starts with ..." condition and have just one alert for all. You can use macros in alert actions to get correct message in email, such as "Test ${TransactionName} was over X seconds for more than 10 minutes.".
If your desired behavior is different, can you provide some example to let me better understand it and help you?
Thank you.