[FLINK-33964][hotfix][docs] Remove useless admin api config options

[leonardBang]

Purpose of the change

Current connector CI did not check the docs build like https://github.com/apache/flink-connector-pulsar/actions/runs/6801264179/job/18506266724
and the docs changed #63 brings a broken url, which lead to FLINK-33964

Brief change log

• remove the outdated url and related doc part

Verifying this change

Please make sure both new and modified tests in this PR follows the conventions defined in our code quality
guide: https://flink.apache.org/contributing/code-style-and-quality-common.html#testing

(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 unit tests
• Added integration tests for end-to-end deployment
• Manually verified by running the Pulsar connector on a local Flink cluster.

Significant changes

(Please check any boxes [x] if the answer is "yes". You can first publish the PR and check them afterwards, for
convenience.)

• Dependencies have been added or upgraded
• Public API has been changed (Public API is any class annotated with @Public(Evolving))
• Serializers have been changed
• New feature has been introduced
  • If yes, how is this documented? (not applicable / docs / JavaDocs / not documented)