Factor out observability from run_tasks and run_tasks_base

[linear]

Currently, run_tasks retrieves a default user from a database and uses its ID for telemetry. It would be nice to have telemetry completely factored out of the implementation of these functions and then injected from outside, for separation of concerns reasons and to facilitate testing.

This will also result in the opportunity to remove this line:

os.system(
"cp cognee/tests/integration/run_toy_tasks/data/cognee_db cognee/.cognee_system/databases/cognee_db"
)

from conftest.py in the run_toy_tasks integration tests.