fix(backup): Suppress verbose SQL error reporting (#56583)

Author: azaslavsky

src/sentry/backup/imports.py

@@ -167,15 +167,18 @@ def _import(
         errs = {field: error for field, error in e.message_dict.items()}
         raise DjangoRestFrameworkValidationError(errs) from e
 
-    sequence_reset_sql = StringIO()
-
+    sql = StringIO()
+    err = StringIO()
     for app in apps.get_app_configs():
-        management.call_command(
-            "sqlsequencereset", app.label, "--no-color", stdout=sequence_reset_sql
-        )
-
+        management.call_command("sqlsequencereset", app.label, "--no-color", stdout=sql, stderr=err)
     with connection.cursor() as cursor:
-        cursor.execute(sequence_reset_sql.getvalue())
+        cursor.execute(sql.getvalue())
+
+    errored = "\n".join(
+        [li for li in err.getvalue().splitlines() if "No sequences found." not in li]
+    ).strip()
+    if errored:
+        raise ValueError(f"Encountered SQL errors:\n\n {errs}")
 
 
 def import_in_user_scope(