intentservice global state (`is_loaded`/`intents_active`) not reset between tests

[patriciapampanelli]

intentservice.is_loaded/intents_active are module globals and no fixture resets them. Suite runs single-process, so whichever test last called load() decides the next test's state.

Observed while reviewing #1775: test_probe_prompt_translation[probes.tap.TAPIntent] flips result by run order alone:

python -m pytest -p no:cacheprovider   "tests/langservice/probes/test_probes_base.py::test_probe_prompt_translation[probes.tap.TAPIntent]" "tests/probes/test_probes.py::test_probe_metadata[probes.audio.AudioAchillesHeel]"  -v
# SKIPPED

python -m pytest -p no:cacheprovider    "tests/probes/test_probes.py::test_probe_metadata[probes.audio.AudioAchillesHeel]" "tests/langservice/probes/test_probes_base.py::test_probe_prompt_translation[probes.tap.TAPIntent]"  -v
# FAILED: assert 0 == 93 (real bug: TAPIntent.probe() never calls get_text)

Pre-existing, outside #1775's diff

Precedent: langservice has the same issue, already fixed via tests/langservice/conftest.py::clear_langprovider_state. Needs the equivalent for intentservice.