how metastore reslove the atomicity when deleting

**Describe the bug**

if we create a namespace a， we will write some nodes in zk

maybe /namespaces/a ,/admin/policies/a. /balance/a some nodes were created

then we delete namespace a, and the pulsar will delete in zk

if deleting /namespaces/a succeeds, but admin/policies/a occurs error, we return an error for the client

but if they delete twice, we judge `/namespaces/a` was deleted, we won't go to the next step

then the zookeeper node will leak.

**To Reproduce**
Steps to reproduce the behavior:
1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

**Expected behavior**

how to keep atomicity in metastore when deleting, if fail,all fail,if succeeds,all succeed

**Screenshots**
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**Desktop (please complete the following information):**
- OS: [e.g. iOS]

**Additional context**
Add any other context about the problem here.

Start by tracing the metastore namespace-deletion path and the ZooKeeper nodes named in the report: /namespaces/a, /admin/policies/a, and /balance/a. Reproduce a partial deletion failure and determine how repeated deletion is handled. Done means the issue has a defined and tested outcome for partial failure and retry behavior.

Written by the indexing model from the issue text.