[Bug] The metric `grpc_open` sometime incorrect

We found the value of `grpc_open` sometime very big(>1000) even no application run in our cluster

No file, test, or entry point is named. Start by reproducing the reported grpc_open value in an otherwise idle cluster and trace where that metric is collected and exposed. Done means the metric no longer reports values above 1000 when no application is running, with a regression test or documented reproduction confirming the behavior.

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