fix flaky subscriber tests
fix flaky subscriber tests

Fixes #9554.

influxdb/influxdb,mark-rushakoff/influxdb,nooproblem/influxdb,influxdb/influxdb,mark-rushakoff/influxdb,influxdata/influxdb,linearb/influxdb,influxdata/influxdb,nooproblem/influxdb,li-ang/influxdb,nooproblem/influxdb,influxdb/influxdb,linearb/influxdb,influxdb/influxdb,mark-rushakoff/influxdb,linearb/influxdb,mark-rushakoff/influxdb,nooproblem/influxdb,nooproblem/influxdb,influxdb/influxdb,influxdb/influxdb,linearb/influxdb,mark-rushakoff/influxdb,mark-rushakoff/influxdb,li-ang/influxdb,linearb/influxdb