fix(@angular/build): safeguard Karma builder stream controller agains… #4000

Job	Run time
list	24s
workflow (build-cli)	1m 51s
workflow (modules-builder-tests)	2m 0s
workflow (devkit-core-tests)	1m 40s
workflow (build-unit-tests)	3m 10s
workflow (devkit-core-tests-rerun)	2m 5s
	11m 10s

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