When using the copy-part API it is expected for s3api to write down an
empty value for X-Object-Sysmeta-S3Api-Etag on segments. This was
ostensibly to prevent writing down an unrelated S3Api-Etag when copying
a part from another MPU the copy transfers object sysmeta. We should
assume a S3Api-Etag w/o X-Static-Large-Object is non-sense, and SLO
should forever expect empty values for it's sysmeta.
Drive-By: consolidate handling of boto2 sigv4 skips
Related-Bug: #2035158
Co-Authored-By: Clay Gerrard <clay.gerrard@gmail.com>
Change-Id: Ic6f04a5a6af8a3e65b226cff2ed6c9fce8ce1fa2