Walk() and Merge code can return dir__XLDIR__ as the last element
on a page list and dir__XLDIR__ as the first element in the next list page.
dir__XLDIR__ is shown in the second-page list because the marker set to
dir/ is meant to skip dir/ and not dir__XLDIR__
To fix this, the code will avoid adding the marker itself to the listing
result.
Bonus fixes, we do not need reload format anymore
as the replaced drive is healed locally we only need
to ensure that drive heal reloads the drive properly.
We preserve the UUID of the original order, this means
that the replacement in `format.json` doesn't mean that
the drive needs to be reloaded into memory anymore.
fixes#10791
Bonus fixes
- logging improvements to ensure that we don't use
`go logger.LogIf` to avoid runtime.Caller missing
the function name. log where necessary.
- remove unused code at erasure sets
