### How to reproduce
1. create a database db1 and a table tbl1;
2. insert some data and export with label L1;
3. drop the db1 and tbl1, and recreate them with same name.
4. insert some data and export with same label L1;
Expect: export success
Actual: error: Label L1 have already been used.
This PR fix it.
Before, the auto analyze job start time was the job creation time, not the start to execute time, which is inaccurate. This pr is to change the start time to the first task start to execute time.
If there exists huge datasets with many database and may tables and many columns, Auto collector might be submit too many jobs which would occupy too much of FE memory.
In this PR, limit job each round could submit up to 5
In the previous PR #27124, we used `objectMapper.readValue` for deserialization. However, this method does not handle null fields, which can lead to issues when upgrading from older versions. Specifically, if a required field is missing in the persistent data, `String realColumnNamesJson = serializeMap.get(REAL_COLUMNS);` will return null, resulting in deserialization errors and frontend startup failure. This issue is likely to occur when upgrading from an older version that uses Jdbc Catalog to a new version including PR #27124. As this represents a specific upgrade scenario involving compatibility with old version data structures, it was not covered in the regular PR test cases. Given the specificity and difficulty in replicating such a scenario, no special test cases were added for this PR.
```
java.lang.NullPointerException: null
at com.sleepycat.je.rep.util.ReplicationGroupAdmin.getMasterSocket(ReplicationGroupAdmin.java:191)
at com.sleepycat.je.rep.util.ReplicationGroupAdmin.doMessageExchange(ReplicationGroupAdmin.java:607)
at com.sleepycat.je.rep.util.ReplicationGroupAdmin.getGroup(ReplicationGroupAdmin.java:406)
at org.apache.doris.ha.BDBHA.getElectableNodes(BDBHA.java:132)
at org.apache.doris.common.proc.FrontendsProcNode.getFrontendsInfo(FrontendsProcNode.java:84)
at org.apache.doris.qe.ShowExecutor.handleShowFrontends(ShowExecutor.java:1923)
at org.apache.doris.qe.ShowExecutor.execute(ShowExecutor.java:355)
at org.apache.doris.qe.StmtExecutor.handleShow(StmtExecutor.java:2113)
...
```
