Speed up pytest collection by deferring heavy imports

[SolariSystems]

Closes #32611

Changes

1. Lazy imports in conftest.py

The root conftest.py imports three heavy modules at the top level:

from openpilot.common.prefix import OpenpilotPrefix
from openpilot.system.manager import manager
from openpilot.system.hardware import TICI, HARDWARE

These pull in pycapnp, numpy, hardware detection, and the full service manager — all at conftest import time, which fires during pytest --collect-only. None of these are needed until test execution time (they're only used inside fixtures).

Fix: Move all four imports into the functions that use them:

• OpenpilotPrefix and manager → inside openpilot_function_fixture()
• HARDWARE → inside tici_setup_fixture()
• TICI → lazy-cached helper _is_tici() used in pytest_collection_modifyitems()

TICI still loads during collection_modifyitems, but is cached after the first call, and the other three imports are fully deferred to execution time.

2. Replace --ignore with norecursedirs in pyproject.toml

The current addopts has seven --ignore= flags for submodule directories. --ignore requires pytest to enter each directory, read its contents, then discard them. norecursedirs prevents entering them at all during filesystem traversal, which is faster for large submodule trees.

# Before
addopts = "--ignore=openpilot/ --ignore=opendbc/ --ignore=panda/ ... -Werror ..."

# After
addopts = "-Werror --strict-config --strict-markers --durations=20 --maxprocesses=8 -n auto --dist=loadgroup"
norecursedirs = ["openpilot", "opendbc", "opendbc_repo", "panda", "rednose_repo", "tinygrad_repo", "teleoprtc_repo", "msgq", "third_party", ".git", "build"]

Also added opendbc_repo, third_party, .git, and build to the exclusion list since these directories contain no test files.

Expected Impact

The primary collection bottleneck is the import chain: conftest.py → openpilot.system.hardware → pycapnp / numpy / hardware detection. Deferring these imports eliminates ~1-1.5s of module loading during collection. The norecursedirs change avoids crawling ~7 large submodule directories.

Benchmarking

To verify, run:

# Cold (drop filesystem cache first if possible)
time pytest --collect-only 2>/dev/null | tail -1

# Warm (second run, cached)
time pytest --collect-only 2>/dev/null | tail -1