ContextOptions cannot be overrided.

[stephpy]

public function setInitOptions(OptionsResolverInterface $resolver)
    {
        $resolver->setDefaults([
            'context' => [
                'limit' => 1000
            ]
        ]);
    }

And

$executionContext->getContextOption('limit'); // return 50.

[tyx]

In the example:
https://github.com/rezzza/jobflow/blob/master/examples/placetostreet-rmq.php

The limit 1 works fine.