chore: Add & re-enable concurrency tests #3979

Job	Run time
apple (macos-14, Xcode_15.2, platform=iOS Simulator,OS=17.2,name=iPhone 15)	9m 40s
linux (jammy, 5.9)	10m 47s
apple (macos-14, Xcode_15.2, platform=tvOS Simulator,OS=17.2,name=Apple TV 4K (3rd generation) (a...	7m 50s
linux (jammy, 6.0)	10m 42s
apple (macos-14, Xcode_15.2, platform=visionOS Simulator,OS=1.0,name=Apple Vision Pro)	7m 6s
linux (amazonlinux2, 5.9)	10m 53s
apple (macos-14, Xcode_15.2, platform=macOS)	11m 17s
linux (amazonlinux2, 6.0)	10m 37s
apple (macos-15, Xcode_16.1, platform=iOS Simulator,OS=18.1,name=iPhone 16)	8m 58s
apple (macos-15, Xcode_16.1, platform=tvOS Simulator,OS=18.1,name=Apple TV 4K (3rd generation) (a...	10m 10s
apple (macos-15, Xcode_16.1, platform=visionOS Simulator,OS=2.1,name=Apple Vision Pro)	9m 5s
apple (macos-15, Xcode_16.1, platform=macOS)	11m 5s
	1h 58m 10s

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