Remove deprecated features from Astro 3.0 #20426

Job	Run time
Build: ubuntu-latest	25s
Build: windows-latest	58s
Lint	1m 8s
Test: ubuntu-latest (node@18)	3m 21s
Test (Smoke): ubuntu-latest (node@18)	2m 50s
Test (E2E): ubuntu-latest (node@18.17.1)	3m 7s
Test: ubuntu-latest (node@20.5.1)	3m 20s
Test (Smoke): windows-latest (node@18)	5m 37s
Test (E2E): windows-latest (node@18.17.1)	4m 46s
Test: macos-latest (node@18)	5m 6s
Test: windows-latest (node@18.17.1)	5m 2s
	35m 40s

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