[SPARK-44223][CORE] Remove LevelDB support

[Hisoka-X]

What changes were proposed in this pull request?

This PR remove LevelDB support

Why are the changes needed?

The leveldb project seems to be no longer maintained, and we can always replace it with rocksdb.

Does this PR introduce any user-facing change?

Yes, the LevelDB will not supported in 4.1.0

How was this patch tested?

exist test.

Was this patch authored or co-authored using generative AI tooling?

No

[Hisoka-X]

cc @LuciferYang @dongjoon-hyun

[LuciferYang]

also cc @mridulm

[LuciferYang]

To @Hisoka-X, perhaps we achieved a limited agreement in the previous pr, but I suggest that it would be better to initiate another relevant discussion on the dev mail list to reach a broader consensus.

[Hisoka-X]

To @Hisoka-X, perhaps we achieved a limited agreement in the previous pr, but I suggest that it would be better to initiate another relevant discussion on the dev mail list to reach a broader consensus.

I sent a discussion in dev mail list. https://lists.apache.org/thread/tvf0msobcg1s3v9x14xtbpb7dgvk3zzj

[mridulm]

@HeartSaVioR has raised a valid concern - what is the path to migration for existing users from leveldb to rocksdb ?

[github-actions]

We're closing this PR because it hasn't been updated in a while. This isn't a judgement on the merit of the PR in any way. It's just a way of keeping the PR queue manageable.
If you'd like to revive this PR, please reopen it and ask a committer to remove the Stale tag!