fix(tests): Fix flaky test_snuba_data timestamp precision

Strip microseconds from the stored event timestamp since nodestore
drops sub-second precision, causing a mismatch with Snuba data.

Fixes #108982

Author: joshuarli

tests/sentry/services/eventstore/test_models.py

@@ -212,7 +212,7 @@ def test_snuba_data(self) -> None:
                 "message": "Hello World!",
                 "tags": {"logger": "foobar", "site": "foo", "server_name": "bar"},
                 "user": {"id": "test", "email": "test@test.com"},
-                "timestamp": before_now(seconds=1).isoformat(),
+                "timestamp": before_now(seconds=1).replace(microsecond=0).isoformat(),
             },
             project_id=self.project.id,
         )