Change parent snapshot ID invariant to a warning

Summary:
After https://github.com/dagster-io/dagster/pull/20335/files, there are edge cases where the parent snapshot ID returned in code might not match up with the parent job snapshot ID stored in the database or in memory for the full job. Rather than invarianting and failing the launched job, warn.

Test Plan:
- Run a grpc server locally, start dagit
- Add a new asset to the job, restart the gRPC server (may need to disable the watcher on dagit that automatically reloads the code location)
- Launch a subsetted job

Before: invariant stops job from launching
Now: warning, job launches just fine

python_modules/dagster/dagster/_core/instance/__init__.py

@@ -1277,14 +1277,16 @@ def _ensure_persisted_job_snapshot(
         check.opt_inst_param(parent_job_snapshot, "parent_job_snapshot", JobSnapshot)
 
         if job_snapshot.lineage_snapshot:
-            if not self._run_storage.has_job_snapshot(
-                job_snapshot.lineage_snapshot.parent_snapshot_id
-            ):
-                returned_job_snapshot_id = self._run_storage.add_job_snapshot(
-                    parent_job_snapshot  # type: ignore  # (possible none)
+            parent_snapshot_id = create_job_snapshot_id(check.not_none(parent_job_snapshot))
+
+            if job_snapshot.lineage_snapshot.parent_snapshot_id != parent_snapshot_id:
+                warnings.warn(
+                    f"Stored parent snapshot ID {parent_snapshot_id} did not match the parent snapshot ID {job_snapshot.lineage_snapshot.parent_snapshot_id} on the subsetted job"
                 )
-                check.invariant(
-                    job_snapshot.lineage_snapshot.parent_snapshot_id == returned_job_snapshot_id
+
+            if not self._run_storage.has_job_snapshot(parent_snapshot_id):
+                self._run_storage.add_job_snapshot(
+                    check.not_none(parent_job_snapshot), parent_snapshot_id
                 )
 
         job_snapshot_id = create_job_snapshot_id(job_snapshot)