This pr is mainly to optimize statistical tasks. Includes the following:
1. No longer generate statistics tasks for empty tables, and move the logic of skipping empty partitions to the process of task generation.
2. Adjusted the default configuration related to statistics to improve the efficiency of statistics collection, parameters include `cbo_concurrency_statistics_task_num`,`statistic_job_scheduler_execution_interval_ms` and `statistic_task_scheduler_execution_interval_ms`.
3. Optimize the display of statistical tasks.
4. In addition, some `org.apache.parquet.Strings` packages are changed to `com.google.common.base.Strings` to avoid the exception that Strings cannot be found in local debug.
etc.
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