test(idempotency): remove standalone test file per maintainer feedback

Tests should be added to existing test files following established patterns, not in new standalone files. The Redis fix will be tested in
_redis/test_redis_layer.py next to the existing test_item_to_datarecord_conversion.

Part of #8090

Signed-off-by: hirenkumar-n-dholariya <hirenkumarnd@gmail.com>

Author: hirenkumar-n-dholariya