operations: fix server side copies on partial upload backends after refactor

After the copy refactor:

179f978f75 operations: refactor Copy into methods on an temporary object

There was some confusion in the code about server side copies - should
they or shouldn't they use partials?

This manifested in unit test failures for remotes which supported
server side Copy and PartialUploads. This combination is rare and only
exists in the sftp backend with the --sftp-copy-is-hardlink flag.

This fix makes the choice that backends which set PartialUploads
always use partials even for server side copies.

fs/operations/copy.go

@@ -146,11 +146,8 @@ func (c *copy) serverSideCopy(ctx context.Context) (actionTaken string, newDst f
 	newDst, err = doCopy(ctx, c.src, c.remoteForCopy)
 	if err == nil {
 		in.ServerSideCopyEnd(newDst.Size()) // account the bytes for the server-side transfer
-		_ = in.Close()
-		c.inplace = true
-	} else {
-		_ = in.Close()
 	}
+	_ = in.Close()
 	if errors.Is(err, fs.ErrorCantCopy) {
 		c.tr.Reset(ctx) // skip incomplete accounting - will be overwritten by the manual copy
 	}