automata: Fix broken universal start states with sparse DFA #2268

Job	Run time
miri-regex-automata	10m 20s
rustfmt	15s
msrv	1m 50s
test (stable, ubuntu-latest, stable)	3m 45s
testfull-regex	3m 44s
test (stable-32, ubuntu-latest, stable, i686-unknown-linux-gnu)	2m 44s
testfull-regex-automata	8m 52s
test (stable-powerpc64, ubuntu-latest, stable, powerpc64-unknown-linux-gnu)	7m 35s
test (stable-s390x, ubuntu-latest, stable, s390x-unknown-linux-gnu)	9m 36s
testfull-regex-capi	23s
test (beta, ubuntu-latest, beta)	3m 58s
testfull-regex-syntax	2m 7s
test (nightly, ubuntu-latest, nightly)	3m 0s
test (macos, macos-latest, stable)	2m 22s
test (win-msvc, windows-latest, stable)	6m 39s
test (win-gnu, windows-latest, stable-x86_64-gnu)	3m 25s
	1h 10m 35s

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