Switching to use Span concurrent map in Scala plugin

[eyalkoren]

Implements #2092 for Scala concurrency plugin

[ghost]

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• Start Time: 2021-12-08T14:04:50.181+0000

• Duration: 66 min 27 sec

• Commit: 4cca40d

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Passed	2627
Skipped	21
Total	2648

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[jackshirazi]

nice simplification! Maybe worth raising an issue for adding span lifecycle tests in scala?

[eyalkoren]

Maybe worth raising an issue for adding span lifecycle tests in scala?

Good idea. We can first review and see what's missing (e.g. trying to propagate and activate a span that is already ended asynchronously). But assuming that this specific PR is not affecting that, I'll merge and keep that separately.