fix: disable sparse output optimization when AST is requested (#352) #1322

Job	Run time
clippy	36s
Analyze (actions)	39s
docs	29s
fmt	16s
test stable --all-features (macos-latest)	2m 56s
test 1.88 (macos-latest)	50s
test stable (windows-latest)	1m 54s
test 1.88 (windows-latest)	1m 55s
test 1.88 (ubuntu-latest)	45s
test stable (ubuntu-latest)	45s
test stable (macos-latest)	47s
feature-checks	2m 59s
test stable --all-features (ubuntu-latest)	1m 30s
doctest	51s
deny / cargo deny check	21s
test stable --all-features (windows-latest)	4m 7s
ci-success	5s
	21m 45s

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