Gracefully terminate active sessions during StreamableHTTP shutdown #1380

Job	Run time
checks / pre-commit	34s
checks / readme-snippets	10s
checks / test (3.10, lowest-direct, ubuntu-latest)	56s
checks / test (3.11, locked, ubuntu-latest)	54s
checks / test (3.11, lowest-direct, windows-latest)	2m 32s
checks / test (3.10, lowest-direct, windows-latest)	2m 34s
checks / test (3.14, lowest-direct, windows-latest)	2m 51s
checks / test (3.11, locked, windows-latest)	3m 29s
checks / test (3.12, locked, windows-latest)	3m 25s
checks / test (3.10, locked, ubuntu-latest)	51s
checks / test (3.12, lowest-direct, windows-latest)	3m 42s
checks / test (3.10, locked, windows-latest)	2m 25s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 21s
checks / test (3.13, locked, ubuntu-latest)	51s
checks / test (3.14, locked, windows-latest)	3m 36s
checks / test (3.13, locked, windows-latest)	2m 20s
checks / test (3.13, lowest-direct, ubuntu-latest)	56s
checks / test (3.11, lowest-direct, ubuntu-latest)	55s
checks / test (3.13, lowest-direct, windows-latest)	3m 50s
checks / test (3.12, locked, ubuntu-latest)	54s
checks / test (3.14, locked, ubuntu-latest)	2m 22s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 2s
all-green	4s
	42m 34s

Provide feedback