PIP-162: Enable system topic by default

[Technoboy-]

Motivation

In PIP-39, we have introduced namespace event to support topic level policy. This feature was released in Pulsar 2.6.

Then PIP-92, we support topic policy to replicate across clusters and release in Pulsar 2.10.

And with version iteration, the corresponding topic policy CLI and functions are mature and stable, but users need to enable system topic to support these features. So it's better to enable system topic by default.

Proposed changes

In 2.11 release, change :

• systemTopicEnabled: false -> true
• topicLevelPoliciesEnabled: false -> true

[asafm]

I think the numbering collides as there is an existing PIP-156

[Technoboy-]

I think the numbering collides as there is an existing PIP-156

Thanks, I have updated it to PIP-162.