[minor][doc][cdc-connector][oracle] Update OracleSchema#getTableSchema doc description

This closes #3443.

Author: ChengJie1053

flink-cdc-connect/flink-cdc-source-connectors/flink-connector-oracle-cdc/src/main/java/org/apache/flink/cdc/connectors/oracle/source/utils/OracleSchema.java

@@ -42,10 +42,7 @@ public OracleSchema() {
         this.schemasByTableId = new HashMap<>();
     }
 
-    /**
-     * Gets table schema for the given table path. It will request to MySQL server by running `SHOW
-     * CREATE TABLE` if cache missed.
-     */
+    /** Gets table schema for the given table path. */
     public TableChange getTableSchema(JdbcConnection jdbc, TableId tableId) {
         // read schema from cache first
         TableChange schema = schemasByTableId.get(tableId);