Add endpoint discovery exception for BaseExecutor

[JohannesMessner]

Problem

Endpoint discovery makes is so that requests do not reach executors where the endpoint doesn't match. For testing purposes, we often don't add an Executor, add BasExecutor will be added automatically. BaseExecutor has no endpoints, so in such a testing scenario, no requests will actually be sent to the worker.

Solution

Add an exception to endpoint discovery s.t. BaseExecutor's always get all requests.

[jina-bot]

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