Add default Origin header for streamable HTTP client #2411

Job	Run time
checks / readme-snippets	12s
checks / pre-commit	35s
checks / test (3.10, lowest-direct, windows-latest)	2m 52s
checks / test (3.11, locked, ubuntu-latest)	53s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 2s
checks / test (3.14, lowest-direct, windows-latest)	2m 30s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 20s
checks / test (3.11, lowest-direct, windows-latest)	3m 14s
checks / test (3.11, lowest-direct, ubuntu-latest)	54s
checks / test (3.12, locked, windows-latest)	3m 27s
checks / test (3.11, locked, windows-latest)	2m 54s
checks / test (3.13, lowest-direct, windows-latest)	2m 20s
checks / test (3.10, locked, windows-latest)	3m 4s
checks / test (3.12, lowest-direct, windows-latest)	4m 25s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 0s
checks / test (3.13, locked, windows-latest)	3m 13s
checks / test (3.12, locked, ubuntu-latest)	1m 2s
checks / test (3.10, lowest-direct, ubuntu-latest)	58s
checks / test (3.14, locked, windows-latest)	4m 7s
checks / test (3.13, locked, ubuntu-latest)	55s
checks / test (3.10, locked, ubuntu-latest)	1m 0s
checks / test (3.14, locked, ubuntu-latest)	2m 29s
all-green	9s
	44m 35s

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