[Hotfix][Zeta] Fix job deadlock when schema change

[hailin0]

Purpose of this pull request

[Zeta] Fix job deadlock when schema change

Execute timeline:

1. runningTask.triggerSchemaChangeBeforeCheckpoint().get() starting
2. SourceFlowLifeCycle#triggerBarrier(Barrier barrier) executed, schemaChangePhase is null at this time
3. runningTask.triggerSchemaChangeBeforeCheckpoint().get() end
4. SourceFlowLifeCycle#notifyCheckpointEnd(long checkpointId) executed, , schemaChangePhase is null at this time
5. schemaChangePhase.set(SchemaChangePhase.createBeforePhase()) executed
6. SourceFlowLifeCycle#collect() execute, check schemaChanging() is true, job enter an endless loop

Does this PR introduce any user-facing change?

No

How was this patch tested?

Check list

• If any new Jar binary package adding in your PR, please add License Notice according
  New License Guide
• If necessary, please update the documentation to describe the new feature. https://github.com/apache/seatunnel/tree/dev/docs
• If you are contributing the connector code, please check that the following files are updated:
  1. Update change log that in connector document. For more details you can refer to connector-v2
  2. Update plugin-mapping.properties and add new connector information in it
  3. Update the pom file of seatunnel-dist
• Update the release-note.

[Hisoka-X]

Please add test case.

[hailin0]

Please add test case.

@Hisoka-X
Currently not possible to add testcase because the ddl event capture has not been developed yet.

[hailin0]

fix #5125