test: Mark flaky tests with run_alone to reduce CI failures

tests/unit/_autoscaling/test_autoscaled_pool.py

@@ -34,6 +34,7 @@ def future(value: T, /) -> Awaitable[T]:
     return f
 
 
+@pytest.mark.run_alone
 async def test_runs_concurrently(system_status: SystemStatus | Mock) -> None:
     done_count = 0
 

tests/unit/_autoscaling/test_snapshotter.py

@@ -146,6 +146,7 @@ def test_snapshot_client_overloaded() -> None:
     assert ClientSnapshot(error_count=7, new_error_count=3, max_error_count=2).is_overloaded
 
 
+@pytest.mark.run_alone
 async def test_get_cpu_sample(
     snapshotter: Snapshotter, event_manager: LocalEventManager, default_memory_info: MemoryInfo
 ) -> None:
@@ -212,6 +213,9 @@ async def test_methods_raise_error_when_not_active() -> None:
         assert snapshotter.active is True
 
 
+@pytest.mark.skip(
+    reason='Flaky due to snapshot pruning boundary condition, see https://github.com/apify/crawlee-python/issues/1734'
+)
 async def test_snapshot_pruning_removes_outdated_records(
     snapshotter: Snapshotter, event_manager: LocalEventManager, default_memory_info: MemoryInfo
 ) -> None:

tests/unit/_utils/test_recurring_task.py

@@ -7,7 +7,6 @@
 import pytest
 
 from crawlee._utils.recurring_task import RecurringTask
-from tests.unit.utils import run_alone_on_mac
 
 
 @pytest.fixture
@@ -42,7 +41,7 @@ async def test_start_and_stop(function: AsyncMock, delay: timedelta) -> None:
     assert rt.task.done()
 
 
-@run_alone_on_mac
+@pytest.mark.run_alone
 async def test_execution(function: AsyncMock, delay: timedelta) -> None:
     task = RecurringTask(function, delay)
 

tests/unit/browsers/test_playwright_browser_controller.py

@@ -47,6 +47,7 @@ async def test_initial_state(browser: Browser) -> None:
     assert controller.has_free_capacity
 
 
+@pytest.mark.run_alone
 async def test_open_and_close_page(controller: PlaywrightBrowserController, server_url: URL) -> None:
     page = await controller.new_page()
     await page.goto(str(server_url))

tests/unit/crawlers/_playwright/test_playwright_crawler.py

@@ -323,6 +323,7 @@ async def some_hook(context: PlaywrightPreNavCrawlingContext) -> None:
     assert handler_data.get('proxy') == proxy_value
 
 
+@pytest.mark.run_alone
 @pytest.mark.parametrize(
     'use_incognito_pages',
     [