[CELEBORN-2242] PushMergedData RPC supports compatible with low version Server

[cxzl25]

What changes were proposed in this pull request?

Why are the changes needed?

A client that supports HARD_SPLIT in PushMergedData will report the following error when accessing a lower version of the Server.

java.nio.BufferUnderflowException
	at java.base/java.nio.Buffer.nextGetIndex(Buffer.java:713)
	at java.base/java.nio.DirectByteBuffer.get(DirectByteBuffer.java:334)
	at org.apache.celeborn.client.ShuffleClientImpl$5.onSuccess(ShuffleClientImpl.java:1430)
	at org.apache.celeborn.common.network.client.TransportResponseHandler.handle(TransportResponseHandler.java:373)
	at org.apache.celeborn.common.network.server.TransportChannelHandler.channelRead(TransportChannelHandler.java:158)

Does this PR resolve a correctness bug?

Does this PR introduce any user-facing change?

How was this patch tested?

local test