Standardize pytest between oss/internal (#21661)

## Summary

Standardizes pytest configuration between the internal and
dagster-oss repositories:

- Shared conftest: internal/conftest.py now delegates to
dagster-oss/conftest.py via importlib instead of duplicating hooks
(--split, pytest_configure, pytest_runtest_setup,
pytest_collection_modifyitems). This keeps dagster-oss standalone while
eliminating drift.
- Aligned pyproject.toml: Both pyproject.toml files now declare the same
pytest settings (addopts, filterwarnings, markers, asyncio_mode,
asyncio_default_fixture_loop_scope, timeout) with consistent comments.
- Removed dead config: Dropped the redundant integration marker
registration from dagster-oss/conftest.py (already in pyproject.toml),
removed unused unit and e2e markers, and removed the no-op
--ignore=dbt/dbt_packages from internal.
- Added comments: Explanatory comments for all pytest config options in
both pyproject.toml files.

## Test plan

Existing test suite.

Internal-RevId: ccdcf06ab2fc3d00e3d38b89225643712c01b969

Author: smackesey

conftest.py

@@ -3,6 +3,9 @@
 
 import pytest
 
+# We have to define these warnings filters here instead of in
+# static config because the dagster package is not guaranteed to be installed
+# in all test suites that use this conftest.py.
 try:
     from dagster import BetaWarning, PreviewWarning, SupersessionWarning
 
@@ -26,11 +29,6 @@ def pytest_configure(config):
     if os.getenv("BUILDKITE"):
         print("+++ Running :pytest: PyTest")  # noqa
 
-    # https://docs.pytest.org/en/7.1.x/example/markers.html#custom-marker-and-command-line-option-to-control-test-runs
-    config.addinivalue_line(
-        "markers", "integration: mark test to skip if DISABLE_INTEGRATION_TESTS is set."
-    )
-
 
 def pytest_runtest_setup(item):
     try:

pyproject.toml

@@ -81,21 +81,49 @@ executionEnvironments = [
 
 [tool.pytest.ini_options]
 
+# Append these options to all pytest invocations.
+addopts = [
+    # Treat unregistered markers as errors to avoid silent typos and ensure all markers are declared in the config. 
+    "--strict-markers",  
+
+    # Show short summary of all non-passing tests (failed, errored, skipped,
+    # etc.) at the end of output.
+    "-ra"
+]
+
+# Don't print any of these warnings during test runs.
 filterwarnings = [
   "ignore::DeprecationWarning",
   "ignore::UserWarning",
   "ignore::pytest.PytestCollectionWarning",
 ]
 
+# Custom markers for categorizing tests. These should be used in test code as
+# `@pytest.mark.<marker_name>`. They can be used to select or deselect tests
+# when running pytest, e.g. `pytest -m "not slow"` to run all tests except
+# those marked as slow.
 markers = [
-  "unit: Fast unit tests with no external dependencies",
   "integration: Tests requiring real git operations or other I/O",
-  "e2e: End-to-end tests requiring GitHub authentication",
   "slow: Tests that take more than 1 second",
 ]
 
-timeout = 240
-addopts = "-ra"
+### pytest-asyncio configuration
+
+# Auto mode: async def test_* functions are automatically treated as async tests without
+# needing @pytest.mark.asyncio on each one. Same for async fixtures.
+asyncio_mode = "auto"
+
+# Use a single event loop for the entire test session, shared across all async fixtures
+# (unless a fixture explicitly declares a different scope).
+asyncio_default_fixture_loop_scope = "session"
+
+### pytest-timeout configuration
+
+# Timeout for individual tests, in seconds. This value is intentionally large
+# as it should not be the default way we catch tests that timeout. The tests
+# themselves should be written such that they fail if something is taking too
+# long. This is just a fallback to ensure our test suite does not hang forever.
+timeout = "240"
 
 # ########################
 # ##### RUFF