[Bug] The pendingRequest resource may leak

#### Expected behavior

When a request error occurs, expect the pendingRequest resource to be shut down normally

#### Actual behavior

When we clean up the cache resources of the producer or consumer on the client side, in fact we need to clean up the corresponding pendingRequest resources at the same time, otherwise it may cause resource leakage

#### Steps to reproduce

For more detailed information, refer to https://github.com/apache/pulsar-client-go/pull/622

Start by reviewing the producer and consumer client-side cache cleanup paths and the pendingRequest behavior described in pull request #622. Verify how request errors are handled and ensure that corresponding pendingRequest resources shut down normally when cache resources are cleaned up; done means the leak scenario is covered without disrupting normal cleanup.

Written by the indexing model from the issue text.