test: Fix flaky integration tests asserting membership in capped iterate() #696

Job	Run time
Docstrings checks / Docstrings checks	16s
Package check / Package check	20s
Tests / Integration tests (3.14, ubuntu-latest)	2m 50s
Doc checks / Doc checks / Docs check	1m 5s
Code checks / Actions lint check	35s
Code checks / Spell check	5s
PR title check	4s
Tests / Integration tests (3.11, ubuntu-latest)	2m 40s
Code checks / Type check / Type check (3.11)	13s
Code checks / Type check / Type check (3.12)	12s
Code checks / Lint check / Lint check (3.14)	13s
Code checks / Lint check / Lint check (3.13)	9s
Code checks / Type check / Type check (3.13)	14s
Code checks / Type check / Type check (3.14)	14s
Tests / Unit tests / Unit tests (ubuntu-latest, 3.14)	41s
Tests / Unit tests / Unit tests (ubuntu-latest, 3.11)	41s
Tests / Unit tests / Unit tests (windows-latest, 3.12)	1m 13s
Tests / Unit tests / Unit tests (windows-latest, 3.14)	1m 1s
Code checks / Lint check / Lint check (3.12)	12s
Tests / Unit tests / Unit tests (ubuntu-latest, 3.13)	47s
Tests / Unit tests / Unit tests (ubuntu-latest, 3.12)	47s
Tests / Unit tests / Unit tests (windows-latest, 3.11)	1m 11s
Tests / Unit tests / Unit tests (windows-latest, 3.13)	1m 9s
Code checks / Lint check / Lint check (3.11)	11s
	17m 3s

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