objtools: fix 5GiB+ server-side copies on S3

[andyasp]

What this PR does

S3 only allows CopyObject to be used on objects <= 5GiB in size (docs). This limitation was encountered when trying to use undelete-blocks on a large block (I anonymized object information):

2024/06/18 12:14:08 ERROR failed to undelete block tenant=(tenant) block=(block) err="The specified copy source is larger than the maximum allowable size for a copy source: 5368709120\nfailed to restore object (tenant)/(block)/index with version (version)

This fix works around this by first checking the object to be copied with a HEAD request to find out its size. If it is small enough to be copied with CopyObject it is. Otherwise if it is too large then a multipart upload is used where each part is an increasing byte range of the object. Minio unfortunately adds an unnecessary HEAD request for each part, but there's no way to work around that while using their client.

Opening as a draft until this is manually tested.

Which issue(s) this PR fixes or relates to

Fixes https://github.com/grafana/mimir-squad/issues/2163

Checklist

• Tests updated.
• Documentation added.
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX].
• about-versioning.md updated with experimental features.

[pstibrany]

lgtm, thank you

[dimitarvdimitrov]

The CHANGELOG has just been cut to prepare for the next Mimir release. Please rebase main and eventually move the CHANGELOG entry added / updated in this PR to the top of the CHANGELOG document. Thanks!

[andyasp]

I finally got around to testing this and opened #9357 as a replacement.