ISSUE-6493: [pulsar-broker] Policies not found

[sijie]

Original Issue: apache#6493

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We got this exception in our production logs:

Policies not found for myTenant/myNamespace namespace
Reason: Policies not found for myTenant/myNamespace namespace

We were able to reproduce it by running this command:

bin/pulsar-admin --admin-url http://broker12.example.com:8080 topics stats persistent://myTenant/myNamespace/myTopic

However, we were only able to reproduce it by running that command on that particular broker (broker12).

This incident happened at the same time as: apache#6492
and apache#6054