[fix][pulsar-io] Fix memory leak in ElasticSearch sink

[nicoloboschi]

Motivation

After #14805, there's a memory leak while using the OpenSearch client.
Every request is kept in a collection, mapping the request with an unique id. The collection is never clear and the objects never collected by the GC.

Modifications

• Refactor the internal mapping needed for access the pulsar record removing the collection and passing the object directly into the callback (using a wrapper object)

Note: this only affects current pulsar master.

• no-need-doc

[nicoloboschi]

@eolivelli @codelipenghui @lhotari @dlg99 PTAL