Use TestFixturesPlugin to Spin up Minio in S3 Plugin Tests

[original-brownbear]

From #37680 (comment)

Instead of keeping a bunch of complicated logic for finding a free port for Minio and retrying starting it from #37747 around, we should move these tests to using the TestFixturesPlugin for spinning up Minio like we do for SMB.

FYI @atorok

[elasticmachine]

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