Fake water blocks can be created by piston arm (client-server inconsistency)

In the latest version 1.21.70.22, there is an inconsistency between the client and server behavior regarding water flow.

Specifically, when a piston arm destroys a water source block, a ghost water block appears on the client side. This ghost block is visually present on the client but does not exist on the server.

Note: This issue is not caused by the piston but rather by a client rendering problem. Please ensure that any fixes target the water behavior and do not modify the piston mechanics, as this could introduce unnecessary new bugs.

Steps to Reproduce:

1. Extend a piston arm.

2. Place a water block in the position where the piston arm is extended.

3. Use a lever to retract and then re-extend the piston arm.

4. Observe the creation of a ghost water block on the client side.

Observed Results:

1. After retracting and re-extending the piston arm, a ghost water block appears on the client.

2. The ghost block is visually present but does not interact as a water block (e.g., entities do not swim in it, and it does not flow).

3. The server correctly recognizes that the water block has been destroyed by the piston.

Expected Results:

1. The water source block should be completely destroyed by the piston arm, and no ghost block should appear on the client side.

2. The client and server should consistently reflect the absence of the water block.