fix(@angular/build): favor istanbul coverage provider when browser te… #3974

Job	Run time
list	34s
workflow (modules-builder-tests)	1m 59s
workflow (devkit-core-tests)	1m 39s
workflow (build-cli)	1m 43s
workflow (devkit-core-tests-rerun)	1m 46s
workflow (build-unit-tests)	2m 56s
	10m 37s

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