chore: restore telemetry by default (#4431)
## Summary
PR #4281 accidentally changed the existing library-load telemetry ping
from default-on/opt-out to explicit opt-in. This PR resumes the existing
library-load telemetry by default when `unstructured` is imported.
## Changes
- Removes the explicit `UNSTRUCTURED_TELEMETRY_ENABLED` gate while
preserving the telemetry endpoint, query payload keys and values,
10-second HTTP timeout, opt-out semantics, and best-effort failure
suppression. The synchronous `nvidia-smi` GPU probe now uses
`subprocess.run` with a 1.0-second timeout and stdin, stdout, and stderr
directed to `DEVNULL`; launch, non-zero-exit, and timeout failures keep
import non-fatal and send `gpu="False"`.
- Users can still turn telemetry off before import by setting either
`DO_NOT_TRACK` or `SCARF_NO_ANALYTICS` to any non-empty value after
trimming whitespace; either variable takes precedence.
- Updates the README disclosure, outbound-connectivity tooling, focused
telemetry coverage, version (`0.26.0`), and changelog.
- Forces `DO_NOT_TRACK=1` in the root pytest `conftest.py` before
ordinary collection, including when an inherited value is empty or
whitespace-only; focused telemetry tests explicitly clear both opt-outs
under mocks to prove default-on behavior.
- Passes `DO_NOT_TRACK=1` after any optional env file in `make
docker-test`, ensuring the packaged Docker test layout opts out before
pytest collection without changing the production image.
## Validation
- Dedicated regressions: 3 failures on the pre-fix implementation, then
3 passes after the bounded probe and forced test opt-out were applied.
- `/opt/homebrew/opt/uv-wrapper/bin/uv run --locked --group test pytest
-q --tb=short test_unstructured/test_telemetry.py` — 21 passed
- `make check` — passed
- `make check-version` — passed
- `git diff --check` — passed
- `shellcheck scripts/image/test-outbound-connectivity.sh
scripts/image/test-all-outbound-connectivity-scenarios.sh` — passed on
the unchanged shell files earlier in this PR
- BCE Junior / Opus and GPT-5.6 Pro Oracle reviews completed;
incorporated the bounded GPU-probe, inherited empty/whitespace, and
packaged Docker test-hermeticity findings.
(authored by codex)
