chore: Use shared mode ApifyStorageClient for test_concurrent_processing_simulation

[Mantisus]

Use ApifyStorageClient(request_queue_access='shared') for test_concurrent_processing_simulation. This is the expected usage for concurrent access.

Issues

Closes: #529

[Pijukatel]

I have a feeling that this test was flaky for the shared client even before the single client was introduced. Could you stress test it a little locally since the CI is now not running integration tests on fork PRs?

[Mantisus]

Could you stress test it a little locally since the CI is now not running integration tests on fork PRs?

Out of about 70 runs, this test failed once due to an actor timeout (execution time exceeding 10 minutes).

But there really is a problem. Normally, it takes less than 10 seconds to execute, but in some runs, it takes up to 5 minutes.

UPD: I will try to find the reasons for this.