Adopt swift-testing for Timeout tests #2525

Job	Run time
Build and Test on swiftlang/swift:nightly-jammy	3m 43s
Integration Tests on swiftlang/swift:nightly-jammy	7m 9s
License Header and Formatting Checks	3m 9s
Performance Tests on swiftlang/swift:nightly-jammy	3m 37s
Build and Test on swiftlang/swift:nightly-6.0-jammy	7m 1s
Integration Tests on swiftlang/swift:nightly-6.0-jammy	9m 54s
Build and Test on swift:5.10.1-noble	3m 57s
Integration Tests on swift:5.10.1-noble	5m 11s
Performance Tests on swiftlang/swift:nightly-6.0-jammy	3m 42s
Build and Test on swift:5.9-jammy	3m 17s
Performance Tests on swift:5.10.1-noble	30s
Integration Tests on swift:5.9-jammy	4m 6s
Build and Test on swift:5.8-focal	2m 59s
Performance Tests on swift:5.9-jammy	30s
Integration Tests on swift:5.8-focal	3m 19s
Performance Tests on swift:5.8-focal	30s
	1h 2m 34s

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