refactor(@angular/build): remove deprecated browser-level isolate option #2416

Job	Run time
list	26s
workflow (modules-builder-tests)	1m 57s
workflow (devkit-core-tests)	1m 20s
workflow (devkit-core-tests-rerun)	1m 12s
workflow (build-unit-tests)	2m 18s
workflow (build-cli)	1m 49s
	9m 2s

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