Usage of Executors in platform context services

Several services that are exposed by the Platform context depend on executors in the implementation details. Today the implementation of the `Metrics` API and the `RecycleBin` implementation both needs parallel execution.

Today we have 2 APIs to get executors: the low level `BaseExecutorFactory` and the `ExecutorFactory`. All service implementation of the services should use at least one of the 2 factories to create executors instead of creating executors "by hand" or using a `ThreadManager`.

Start by locating the Platform context implementations of the Metrics API and RecycleBin, then inspect their executor creation and ThreadManager usage. Compare those implementations with BaseExecutorFactory and ExecutorFactory; the work is done when affected service implementations obtain executors through one of the two factories.

Written by the indexing model from the issue text.