[fix][doc] Fix wrong description of `pulsar.allocator.leak_detection` and remove 'Client memory allocator configuration' section from the old version doc

[RobertIndie]

Fixes #16804

Motivation

The property "pulsar.allocator.leak_detection" has wrong description: "Service URL provider for Pulsar service" in https://pulsar.apache.org/docs/client-libraries-java/#client-memory-allocator-configuration.

In addition, this PR also remove 'Client memory allocator configuration' section from the old version doc. This section should only appear after 2.10.0 and seems to be mistakenly added to the old version. See this PR: https://github.com/apache/pulsar/pull/12481

Modifications

• Fix the wrong description.
• Remove 'Client memory allocator configuration' section from the old version doc.

Documentation

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