fix(integrationtests): replace minio with seaweedfs

[JiahuiWho]

What

Replace the MinIO test container with SeaweedFS (chrislusf/seaweedfs:4.46)

Why

MinIO deleted its Docker Hub images and breaks CI run.

Known limitations

N/A

Issue that this PR addresses

N/A

Checklist

PR Structure

• It is not possible to break this PR down into smaller PRs.
• This PR does not mix refactoring changes with feature changes.
• This PR's title starts with name of package that is most changed in the PR, or all if the changes are broad or impact many packages.

Thoroughness

• This PR adds tests for the new functionality or fixes.
• All updated queries have been tested (refer to this check if the data set returned by the updated query is expected to be same as the original one).

Release

• This is not a breaking change.
• This is ready to be tested in development.
• The new functionality is gated with a feature flag if this is not ready for production.

[Copilot]

Pull request overview

Replaces the unavailable MinIO integration-test dependency with pinned SeaweedFS while preserving S3-backed migration coverage.

Changes:

• Adds and initializes a SeaweedFS object-store container.
• Updates datastore credentials, endpoints, exporter naming, and cleanup.
• Migrates the protocol migration test to the renamed infrastructure.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
internal/integrationtests/infrastructure/main_setup.go	Initializes and cleans up the object store.
internal/integrationtests/infrastructure/ledger_exporter.go	Configures SeaweedFS-compatible S3 access.
internal/integrationtests/infrastructure/containers.go	Defines SeaweedFS startup and readiness.
internal/integrationtests/data_migration_test.go	Uses the renamed object-store container.

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