Unify the return type of `executeQuery` in java sdk Statement

the return type of statement has two types (SQLResultSet and java.sql.Result) currently. it's better to unify to java.sql.ResultSet

Find the Java SDK's Statement class and its executeQuery method. Identify the two return types (SQLResultSet and java.sql.Result). Understand the project's SQL execution flow to decide how to unify them to java.sql.ResultSet. Check existing tests for executeQuery to ensure compatibility after the change.

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