fix(java-binding): use table committed epoch in demo query

[wenym1]

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What's changed and what's your intention?

Previously in the java-binding demo ci test, we use the max_committed_epoch in hummock version as the query epoch. However, after we deprecate the max_committed_epoch in hummock version, the value in the protobuf becomes 0, and with this invalid max committed epoch, we are not able to query the correct data.

In this PR, we change to use the committed_epoch of the table as the query epoch.

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