All resources in channel-broker and mt-channel-broker have been defined twice

[houshengbo]

Describe the bug
All resources in channel-broker and mt-channel-broker have been defined twice.

Expected behavior
All resources in channel-broker and mt-channel-broker should be defined only once.

To Reproduce
Check the yaml files of channel-broker and mt-channel-broker.

Knative release version
0.14.x

Additional context
Add any other context about the problem here such as proposed priority