chore(env): update ARTIFACT_BACKEND_VERSION

[droplet-bot]

Because

• The version of the artifact-backend service is not updated in the instill-core repository.

This commit

• updates the ARTIFACT_BACKEND_VERSION in the .env file to efc589e.
• updates the artifactBackend.image.tag in the helm chart values.yaml file to efc589e.

Changes in artifact-backend

• feat(kb): implement zero-downtime KB update (feat(kb): implement zero-downtime KB update artifact-backend#273)
• refactor(worker): implement symmetric cleanup patterns and simplify embedding workflow (refactor(worker): implement symmetric cleanup patterns and simplify embedding workflow artifact-backend#272)
• feat(ai): add multi-provider support with OpenAI for legacy embeddings (feat(ai): add multi-provider support with OpenAI for legacy embeddings artifact-backend#271)
• refactor(artifact): simplify chunk retrieval and align chunk type naming with protobuf (refactor(artifact): simplify chunk retrieval and align chunk type naming with protobuf artifact-backend#270)
• refactor(embeddings): replace preset pipeline with direct model API call (refactor(embeddings): replace preset pipeline with direct model API call artifact-backend#269)
• chore(main): revert back to previous value scheme (chore(main): revert back to previous value scheme artifact-backend#268)