IODEMO: fix progress loop

[evgeny-leksikov]

What

Fix progress loop in io_demo

Why

Fixes a hang in io_demo test over shared memory transport

How

If progress_worker_event() returns false, we don't progress the io message. We have to progress io_msg and worker at least once to avoid the situation when io_msg is completed on previous iteration of worker progress.
The issue is stable reproducible with shared memory transport

[yosefe]

what failure does it fix?

[evgeny-leksikov]

what failure does it fix?

stuck with UCX_TLS=rc_x,shm

[yosefe]

because progress_worker_event() returns false and we don't progress the io message?

[evgeny-leksikov]

because progress_worker_event() returns false and we don't progress the io message?

exactly

[yosefe]

pls update PR description with issue symptom

[evgeny-leksikov]

pls update PR description with issue symptom

done

[changchengx]

Under shm transports, io_demo works with this PR.

[evgeny-leksikov]

/azp run

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