[fix] revert IMAP cache data field type to compatible with old version

[liunaijie]

Purpose of this pull request

fix #6853

Does this PR introduce any user-facing change?

How was this patch tested?

using exist test.

we need conside how to test the version compatible.

now we can't save binary file to github, so we can't read from binary file to check whether compatible with current. and we can't gererate the old version cache data from current version.

now just revert the code.

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]

now we can't save binary file to github, so we can't read from binary file to check whether compatible with current. and we can't gererate the old version cache data from current version.

We can use old version jar to submit job then get binary file. Then use new version jar to submit job and read binary file. It's all in docker. So I think it should be worked.

[liunaijie]

if we fix it in version 2.3.6 , it still has issue when upgrade from 2.3.5. but it's ok for older version like 2.3.4.
if we not fix it, it will be ok when upgrade from 2.3.5. but will has issue when from version before 2.3.4

[Hisoka-X]

if we fix it in version 2.3.6 , it still has issue when upgrade from 2.3.5. but it's ok for older version like 2.3.4. if we not fix it, it will be ok when upgrade from 2.3.5. but will has issue when from version before 2.3.4

Yes, we should fix it before release 2.3.6. Could you create an issue about add test case for imap upgrade?

[Hisoka-X]

if we fix it in version 2.3.6 , it still has issue when upgrade from 2.3.5. but it's ok for older version like 2.3.4. if we not fix it, it will be ok when upgrade from 2.3.5. but will has issue when from version before 2.3.4

Yes, we should fix it before release 2.3.6. Could you create an issue about add test case for imap upgrade?

Added #7055