Fix flaky TestS3WrongRegionPicked.testS3WrongRegionSelection

[skrzypo987]

Description

The trino-hive testsing suite has been run 5x on github actions and it passes, so it will hopefully work.

Non-technical explanation

Fixes #14568

Release notes

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# Section
* Fix some things. ({issue}`issuenumber`)

[Praveen2112]

Can we add a comment on why we need this random bucket name ?

[Dith3r]

MinioClient has something which is called createdBuckets which is static. Event if we start new Minio container, this will fail to create bucket with same name.

[Praveen2112]

But in the new minio container, the bucket doesn't exist right ?

[Dith3r]

In MinioClient class from package io.trino.testing.minio we have a set of created buckets (which is persistent and independent of minio container and its buckets). Maybe we should clean this set on close?

Edit: If we do this test in loop, same name error will be a thing that will come up as first. I don't know if this is a reason for being flaky.

[skrzypo987]

This MinioClient class is strictly for testing purposes, so forcing a unique bucket naming seems like a good idea. If I had thought about it in the first place, there would be no bug.

[Dith3r]

I would look up on BackgroundHiveSplitLoader if it behaves correctly when stopped and loadSplits is ongoing.

[Praveen2112]

nit: Can we useString.format

[skrzypo987]

I actually prefer concatenation for trivial cases.