Fix flaky LangGraph timeout tests #5008

Job	Run time
test-latest-deps	1m 42s
check-protos	7m 39s
cloud-test	1m 48s
features-tests / test	8m 2s
build-lint-test (3.14, ubuntu-latest)	2m 53s
build-lint-test (3.10, ubuntu-latest)	1m 34s
build-lint-test (3.10, ubuntu-arm)	2m 42s
build-lint-test (3.14, macos-arm)	2m 18s
build-lint-test (3.10, macos-arm)	2m 59s
build-lint-test (3.10, windows-latest)	3m 59s
build-lint-test (3.14, macos-intel)	7m 13s
build-lint-test (3.10, macos-intel)	6m 27s
build-lint-test (3.14, ubuntu-arm)	2m 45s
build-lint-test (3.14, windows-latest)	3m 51s
	55m 52s

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