fix(ASGI mounts): Prevent accidental scope overrides by mounted ASGI apps #4664

Job	Run time
mypy	1m 1s
slotscheck	18s
pyright	44s
Test server integration (uvicorn<0.27.0)	41s
Test Minimal Application with Base Dependencies	12s
validate	17s
Test server integration (uvicorn>=0.27.0)	44s
Test Minimal Pydantic 1 application	15s
test-platform-compat	0s
test (3.10) / test	1m 50s
test (3.11) / test	1m 39s
test (3.12) / test	3m 8s
test (3.13) / test	2m 1s
test (3.8) / test	2m 41s
test (3.9) / test	1m 52s
build-docs	1m 21s
upload-test-coverage	20s
codeql	2m 9s
sonar	1m 0s
	22m 13s

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