[Playground] ci/cd concurrency fixed

[eantyshev]

Unfortunately, BEAM_CONCURRENCY didn't actually work: every task needed to acquire the semaphore

Tested locally using ci_cd.py

Thanks, @olehborysevych for pointing out!

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[olehborysevych]

LGTM. Tested with deployment to demo environment.

[olehborysevych]

R: @damccorm

[github-actions]

Stopping reviewer notifications for this pull request: review requested by someone other than the bot, ceding control

[damccorm]

LGTM, thanks!