Fix config issue that potentially caused some alert not sent (#1515)
Fix config issue that potentially caused some alert not sent (#1515)

Same error pattern should not appear more than once in the config.
The monitoring tool only looks at the first matching error pattern in the config.

The mis-config likely caused the issue https://github.com/knative/test-infra/issues/1513
knative/test-infra,knative/test-infra,knative/test-infra