[BUG] msgRateIn and msgThroughputIn is 0

[dockerzhang]

Describe the bug
msgRateIn and msgThroughputIn is 0

To Reproduce
Steps to reproduce the behavior:

1. produce message use client.
2. get metrics to use command or grafana dashboard.

Screenshots

Additional context
After #228 be merged, bytesInCounter and msgInCounter is available, but msgRateIn and msgThroughputIn is update by MessagePublishContext in pulsar.