Incorrect implementation of condition variable

https://github.com/apache/pulsar-client-go/blob/master/pulsar/internal/channel_cond.go#L60

Why would a condition variable need to return a value by default?

This will cause the CPU usage of the producer process to spike during a failure.

Read pulsar/internal/channel_cond.go around line 60 and inspect how the condition variable behaves when the producer encounters a failure. Reproduce or observe the failure path, then verify that the condition variable does not return a value by default or cause a producer CPU spike; run the relevant existing tests if available.

Written by the indexing model from the issue text.