Deflake the issue-1363 tests: wait for lifespan startup instead of sl… #2715

Job	Run time
checks / pre-commit	38s
checks / readme-snippets	14s
checks / test (3.10, locked, ubuntu-latest)	57s
checks / test (3.13, lowest-direct, windows-latest)	2m 0s
checks / test (3.11, lowest-direct, windows-latest)	1m 34s
checks / test (3.13, locked, windows-latest)	1m 18s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 28s
checks / test (3.13, locked, ubuntu-latest)	50s
checks / test (3.12, lowest-direct, windows-latest)	1m 38s
checks / test (3.11, locked, ubuntu-latest)	52s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 31s
checks / test (3.14, locked, ubuntu-latest)	1m 56s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 20s
checks / test (3.10, lowest-direct, windows-latest)	1m 26s
checks / test (3.10, locked, windows-latest)	1m 33s
checks / test (3.12, locked, windows-latest)	1m 27s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 28s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 32s
checks / test (3.11, locked, windows-latest)	1m 56s
checks / test (3.12, locked, ubuntu-latest)	58s
checks / test (3.14, lowest-direct, windows-latest)	1m 54s
checks / test (3.14, locked, windows-latest)	2m 12s
all-green	2s
	30m 44s

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