[Enhancement] Migrate Paimon C++ dependency to the official Apache release

[lxy-9602]

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Description

Hi Doris community,

Paimon C++ has been migrated to the Apache community, and future releases
and ongoing development will continue in the official repository:

https://github.com/apache/paimon-cpp

We noticed that Doris currently uses an older Paimon C++ snapshot from
apache/doris-thirdparty:

https://github.com/apache/doris/blob/master/thirdparty/arrow-paimon-vars.sh

When convenient, it would be great to migrate this dependency to an
official Apache Paimon C++ release, such as 0.3.0, so that Doris can more
easily receive future updates and bug fixes.

Please note that the current snapshot does not have an identical commit SHA
in the Apache repository, so the migration may require compatibility
validation rather than only changing the download URL.

Solution

We suggest:

1. Updating the dependency to an official Apache Paimon C++ release.
2. Reviewing the existing Doris-specific patches and build configuration.
3. Verifying the Doris BE build and related Paimon tests.

Apache Paimon C++ 0.3.0 release:

https://github.com/apache/paimon-cpp/releases/tag/v0.3.0

If any issues arise during the migration, we would be happy to help.

Are you willing to submit PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct