Revert "Adopt h2handler multiplexer (#1587)" (#1641) #852

Job	Run time
License Header and Formatting Checks	2m 24s
Build and Test on swiftlang/swift:nightly-focal	4m 58s
Build and Test on swift:5.8-jammy	4m 10s
Build and Test on swift:5.7-jammy	3m 50s
Build and Test on swift:5.6-focal	3m 15s
Integration Tests on swiftlang/swift:nightly-focal	3m 35s
Integration Tests on swift:5.8-jammy	3m 42s
Integration Tests on swift:5.7-jammy	3m 26s
Integration Tests on swift:5.6-focal	3m 21s
Performance Tests on swiftlang/swift:nightly-focal	10m 24s
Performance Tests on swift:5.8-jammy	9m 17s
Performance Tests on swift:5.7-jammy	9m 8s
Performance Tests on swift:5.6-focal	8m 59s
	1h 10m 29s

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