feat: deprecate `contrib.opentelemetry` #6268

Job	Run time
validate	20s
mypy	1m 8s
pyright	37s
Test server integration (uvicorn>=0.27.0)	1m 2s
slotscheck	18s
Test Minimal Application with Base Dependencies	18s
Test server integration (uvicorn<0.27.0)	45s
test_typing_extensions (4.12.1)	16s
test_typing_extensions (latest)	20s
Test Minimal Pydantic 1 application	22s
test_typing_extensions (4.13.1)	21s
test-platform-compat	0s
test (3.13) / test	1m 41s
test (3.9) / test	2m 6s
test (3.10) / test	1m 40s
test (3.11) / test	1m 32s
test (3.12) / test	2m 19s
build-docs	3m 1s
test_success	2s
upload-test-coverage	19s
codeql	2m 16s
	20m 43s

Provide feedback