fix(@angular/ssr): improve locale handling in app-engine #2261

Job	Run time
build	19s
build-e2e-windows	31s
lint	2m 20s
publish-snapshots	-1s
Browser Compatibility Tests	-1s
test	-1s
e2e-snapshots	0s
e2e-package-managers	0s
e2e	0s
e2e-windows	0s
	3m 7s

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