chore: Remove retry-after header support #3956

Job	Run time
apple (macos-14, Xcode_15.2, platform=iOS Simulator,OS=17.2,name=iPhone 15)	10m 15s
apple (macos-14, Xcode_15.2, platform=tvOS Simulator,OS=17.2,name=Apple TV 4K (3rd generation) (a...	12m 8s
apple (macos-14, Xcode_15.2, platform=visionOS Simulator,OS=1.0,name=Apple Vision Pro)	34m 52s
linux (jammy, 5.9)	11m 44s
apple (macos-14, Xcode_15.2, platform=macOS)	12m 31s
apple (macos-15, Xcode_16.1, platform=iOS Simulator,OS=18.1,name=iPhone 16)	8m 10s
linux (jammy, 6.0)	11m 17s
apple (macos-15, Xcode_16.1, platform=tvOS Simulator,OS=18.1,name=Apple TV 4K (3rd generation) (a...	6m 29s
linux (amazonlinux2, 5.9)	12m 3s
apple (macos-15, Xcode_16.1, platform=visionOS Simulator,OS=2.1,name=Apple Vision Pro)	8m 33s
linux (amazonlinux2, 6.0)	11m 17s
apple (macos-15, Xcode_16.1, platform=macOS)	11m 18s
	2h 30m 37s

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