[INLONG-7882][Sort] Oracle CDC reduces the number of session connections

[e-mhui]

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[INLONG-7882][Sort] Oracle CDC reduces the number of session connections

• Fixes [Improve][Sort] Oracle CDC reduces the number of session connections #7882

Motivation

Oracle CDC reduces the number of session connections.
We use oracle connection in context for each reader subtask, Instead of creating a new oracle connection every time.

Modifications

Use oracle connection in context for each reader subtask.

 public void configure(SourceSplitBase sourceSplitBase) {
        /**...**/       
        this.databaseSchema = OracleUtils.createOracleDatabaseSchema(connectorConfig, connection);
       /**...**/
}