feat: add sample code for multiple inequalities filter

[kevkim-codes]

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https://buganizer.corp.google.com/issues/352502736

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[snippet-bot]

Here is the summary of changes.

You are about to add 1 region tag.

• samples/snippets/src/main/java/com/example/datastore/filters/MultiIneqFilter.java:39, tag datastore_query_filter_compound_multi_ineq

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[minherz]

Please have a look at a few nit comments.