[refactor][client] Remove cpp and python client in 2.10

[liangyepianzhou]

Motivation

The cpp client and python client have been removed to https://github.com/apache/pulsar-client-cpp and https://github.com/apache/pulsar-client-python. It should be excluded from branch-2.10 now.

Modifications

Remove cpp client and python client in branch-2.10.

Verifying this change

• Make sure that the change passes the CI checks.

(Please pick either of the following options)

This change is a trivial rework / code cleanup without any test coverage.

(or)

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

(or)

This change added tests and can be verified as follows:

(example:)

• Added integration tests for end-to-end deployment with large payloads (10MB)
• Extended integration test for recovery after broker failure

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:

[tisonkun]

I guess we need to update the CI workflow and check suite (.asf.yaml) also.

[liangyepianzhou]

Integration tests seem to require building a Python instant.

[liangyepianzhou]

Close this via #20981