fix: address flaky tests (#3363)

fix: resolve flaky tests and race conditions in test suite

- Fix telemetry/event tests by patching class methods instead of instances
- Use unique temp files/directories to prevent CI race conditions
- Reset singleton state between tests
- Mock embedchain.Client.setup() to prevent JSON corruption
- Rename test files to test_*.py convention
- Move agent tests to tests/agents directory
- Fix repeated tool usage detection
- Remove database-dependent tools causing initialization errors

tests/cli/authentication/test_utils.py

@@ -108,7 +108,9 @@ class TestValidateToken(unittest.TestCase):
 
 
 class TestTokenManager(unittest.TestCase):
-    def setUp(self):
+    @patch("crewai.cli.authentication.utils.TokenManager._get_or_create_key")
+    def setUp(self, mock_get_key):
+        mock_get_key.return_value = Fernet.generate_key()
         self.token_manager = TokenManager()
 
     @patch("crewai.cli.authentication.utils.TokenManager.read_secure_file")