Add topologyspreadconstraint to deploy pods in sts cross different az evenly

[wangshu3000]

Fixes https://github.com/apache/pulsar-helm-chart/issues/521

Motivation

I see broker sts doesn't support topology constraint configuration. That means 2 pods in the sts may possible depoyed to on az in kubernetes cluster. Reference doc: https://kubernetes.io/docs/concepts/scheduling-eviction/topology-spread-constraints/

Modifications

Added a topology spread constraint configuration to deployed the pods in sts spread to different az, so that under an AZ outage, the impact can be only limited to small number of brokers.

Verifying this change

• [ ] Make sure that the change passes the CI checks.

[lhotari]

Closing and reopening to trigger a new GitHub Actions workflow run after 6b31946fc791105a0800a81ddb9d7f78879f2d33