fix(http2): fix internals of HTTP/2 CONNECT upgrades #3074

Job	Run time
Check Style	8s
Verify hyper.h is up to date	2m 20s
semver	24s
Test with Miri	48s
Check MSRV	4m 26s
features	37s
Test C API (FFI)	36s
Test cargo-c support (FFI)	20s
Test stable on ubuntu-latest	22s
Test beta on macOS-latest	36s
Test stable on macOS-latest	25s
Test nightly on ubuntu-latest	1s
Test stable on windows-latest	53s
Test beta on windows-latest	34s
Test nightly on windows-latest	41s
Test nightly on macOS-latest	41s
Test beta on ubuntu-latest	34s
minimal-versions	41s
udeps	25s
Check exposed types	-1s
Build docs	-1s
CI is green	0s
	15m 30s

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