chore: restructure test env, cassettes, and conftest; fix flaky tests

Consolidates pytest config, standardizes env handling, reorganizes cassette layout, removes outdated VCR configs, improves sync with threading.Condition, updates event-waiting logic, ensures cleanup, regenerates Gemini cassettes, and reverts unintended test changes.

lib/crewai/tests/tools/test_tool_usage.py

@@ -564,16 +564,23 @@ def test_tool_validate_input_error_event():
         patch("json_repair.repair_json", side_effect=Exception("Failed to repair")),
     ):
         received_events = []
+        condition = threading.Condition()
 
         @crewai_event_bus.on(ToolValidateInputErrorEvent)
         def event_handler(source, event):
-            received_events.append(event)
+            with condition:
+                received_events.append(event)
+                condition.notify()
 
         # Test invalid input
         invalid_input = "invalid json {[}"
         with pytest.raises(Exception):  # noqa: B017
             tool_usage._validate_tool_input(invalid_input)
 
+        with condition:
+            if not received_events:
+                condition.wait(timeout=5)
+
         # Verify event was emitted
         assert len(received_events) == 1, "Expected one event to be emitted"
         event = received_events[0]