Replace udp_transceiver.cpp::txLoop 50us poll with busy loop

[eliotheinrich]

Testing the realtime decoding server in CUDA-QX uncovered the udp_transceiver.cpp::txLoop polling granularity as a major factor in UDP latency. This PR replaces the 50us poll with a busy-loop.

[Renaud-K]

LGTM. Thank you!

[github-actions]

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