feat(llmobs): improve langchain llmobs span names #47180

Job	Run time
test_unit (dd-lib-python-init-test-django)	3m 35s
test_unit (dd-lib-python-init-test-django-gunicorn)	3m 18s
test_unit (dd-lib-python-init-test-django-gunicorn-alpine)	3m 22s
test_unit (dd-lib-python-init-test-django-uvicorn)	3m 25s
test_unit (dd-lib-python-init-test-django-no-perms)	3m 26s
test_unit (dd-lib-python-init-test-django-pre-installed)	3m 32s
test_unit (dd-lib-python-init-test-django-unsupported-python)	3m 39s
build-and-publish-test-image / wait_for_package	8s
build-and-publish-test-image / build_push / build_push	12m 35s
test-runner-test (dd-lib-python-init-test-django)	6m 5s
test-runner-test (dd-lib-python-init-test-django-gunicorn)	6m 22s
test-runner-test (dd-lib-python-init-test-django-uvicorn)	6m 14s
	55m 41s

Provide feedback