hang when client receives header response that's too big in http2

[ajwerner]

Version
Hyper @ 7de0237

Platform
Linux 6.5.0-42-generic

Description
When the server sends a response with headers that are too big, hyper can sometimes just hang.

I wrote this test:

hyper/tests/integration.rs

Lines 64 to 86 in bdd112e

	// Test that clients get responses when the server sends a response with
	// headers that are too large by just a bit.
	t! {
	long_header_response,
	client:
	request:
	;
	response:
	status: 500,
	headers: {
	},
	;
	server:
	request:
	;
	response:
	status: 500,
	headers: {
	// Just above DEFAULT_SETTINGS_MAX_HEADER_LIST_SIZE.
	"error" => ("a".repeat(16 << 10 + 1)),
	},
	;
	}

I expected to see an error. Instead the test just blocks forever.

See hyperium/tonic#1834 and https://discord.com/channels/500028886025895936/1268954374634471484 for context.