feat: improve default configuration of auto partitioning

Author: gyang94

fluss-common/src/main/java/com/alibaba/fluss/config/ConfigOptions.java

@@ -936,9 +936,10 @@ public class ConfigOptions {
     public static final ConfigOption<AutoPartitionTimeUnit> TABLE_AUTO_PARTITION_TIME_UNIT =
             key("table.auto-partition.time-unit")
                     .enumType(AutoPartitionTimeUnit.class)
-                    .noDefaultValue()
+                    .defaultValue(AutoPartitionTimeUnit.DAY)
                     .withDescription(
                             "The time granularity for auto created partitions. "
+                                    + "The default value is 'DAY'. "
                                     + "Valid values are 'HOUR', 'DAY', 'MONTH', 'QUARTER', 'YEAR'. "
                                     + "If the value is 'HOUR', the partition format for "
                                     + "auto created is yyyyMMddHH. "
@@ -961,20 +962,21 @@ public class ConfigOptions {
     public static final ConfigOption<Integer> TABLE_AUTO_PARTITION_NUM_PRECREATE =
             key("table.auto-partition.num-precreate")
                     .intType()
-                    .defaultValue(4)
+                    .defaultValue(2)
                     .withDescription(
                             "The number of partitions to pre-create for auto created partitions in each check for auto partition. "
+                                    + "The default value is 2, which means 2 partitions will be pre-created. If the 'table.auto-partition.time-unit' is 'DAY'(default), one precreated partition is for today and another one is for tomorrow. "
                                     + "For example, if the current check time is 2024-11-11 and the value is "
                                     + "configured as 3, then partitions 20241111, 20241112, 20241113 will be pre-created. "
                                     + "If any one partition exists, it'll skip creating the partition.");
 
     public static final ConfigOption<Integer> TABLE_AUTO_PARTITION_NUM_RETENTION =
             key("table.auto-partition.num-retention")
                     .intType()
-                    .defaultValue(-1)
+                    .defaultValue(7)
                     .withDescription(
                             "The number of history partitions to retain for auto created partitions in each check for auto partition. "
-                                    + "The default value is -1 which means retain all partitions. "
+                                    + "The default value is 7 which means retains 7 partitions. "
                                     + "For example, if the current check time is 2024-11-11, time-unit is DAY, and the value is "
                                     + "configured as 3, then the history partitions 20241108, 20241109, 20241110 will be retained. "
                                     + "The partitions earlier than 20241108 will be deleted.");

fluss-connectors/fluss-connector-flink/src/test/java/com/alibaba/fluss/connector/flink/source/FlinkTableSourceBatchITCase.java

@@ -283,7 +283,7 @@ void testLimitLogTableScan() throws Exception {
     @ValueSource(booleans = {true, false})
     void testCountPushDown(boolean partitionTable) throws Exception {
         String tableName = partitionTable ? preparePartitionedLogTable() : prepareLogTable();
-        int expectedRows = partitionTable ? 20 : 5;
+        int expectedRows = partitionTable ? 10 : 5;
         // normal scan
         String query = String.format("SELECT COUNT(*) FROM %s", tableName);
         assertThat(tEnv.explainSql(query))