fix(@angular/build): favor istanbul coverage provider when browser te… #3975

Job	Run time
list	25s
workflow (modules-builder-tests)	2m 25s
workflow (devkit-core-tests)	1m 23s
workflow (devkit-core-tests-rerun)	1m 29s
workflow (build-cli)	1m 47s
workflow (build-unit-tests)	2m 27s
	9m 56s

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