[improve][cli]New tests for operations on namespaces in pulsar-client-tools

[sandeep-mst]

Fixes 21743 of apache/pulsar

Motivation

Pulsar client tools doesn't have tests for listing, deleting and creating namespaces through Pulsar-admin.

Modifications

Modified TestCmdNamespaces.java and added tests for listing, creating and deleting namespaces. These tests test with V2 namespace convention.

Verifying this change

• Make sure that the change passes the CI checks.

(Please pick either of the following options)

This change is already covered by existing tests, such as (please describe tests).

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository:
cognitree#10