Clean log buffer in tests. (#37675)

Co-authored-by: Maksim Sadym <sadym@google.com>
diff --git a/webdriver/tests/bidi/log/entry_added/event_buffer.py b/webdriver/tests/bidi/log/entry_added/event_buffer.py
index c30ad8a..69c96c8 100644
--- a/webdriver/tests/bidi/log/entry_added/event_buffer.py
+++ b/webdriver/tests/bidi/log/entry_added/event_buffer.py
@@ -10,6 +10,10 @@
 async def test_console_log_cached_messages(
     bidi_session, wait_for_event, log_type, new_tab
 ):
+    # Clear events buffer.
+    await bidi_session.session.subscribe(events=["log.entryAdded"])
+    await bidi_session.session.unsubscribe(events=["log.entryAdded"])
+
     # Log a message before subscribing
     expected_text = await create_log(bidi_session, new_tab, log_type, "cached_message")
 
@@ -63,6 +67,10 @@
 async def test_console_log_cached_message_after_refresh(
     bidi_session, subscribe_events, new_tab, log_type
 ):
+    # Clear events buffer.
+    await bidi_session.session.subscribe(events=["log.entryAdded"])
+    await bidi_session.session.unsubscribe(events=["log.entryAdded"])
+
     # Track all received log.entryAdded events in the events array
     events = []