maybe fixes #126609

[ankit--sethi]

As outlined in #126609, TransportSamlLogoutAction and TransportSamlInvalidateSessionAction have a gap in their implementation where execution occurring on the generic thread pool unintentionally forks to a transport_worker thread. This is related to usage of client::get and client::bulk methods within the flow, where client refers to NodeClient that will always execute a given task on a transport worker thread. (see NodeClient.executeLocally and the discussion here.

This change refactors the existing consumers and wraps them such that the follow up work after we have retrieved GetResponse/BulkResponse is re-directed back to the generic thread pool, i.e. after client has done its job retrieving these responses.