fix: preserve data on self metadata copy (#2819)

Co-authored-by: cxymds <Cxymds@qq.com>

crates/ecstore/src/set_disk/write.rs

@@ -402,7 +402,7 @@ impl SetDisks {
         disks: &[Option<DiskStore>],
         opts: &UpdateMetadataOpts,
     ) -> disk::error::Result<()> {
-        if fi.metadata.is_empty() {
+        if fi.metadata.is_empty() && !opts.replace_user_metadata {
             return Ok(());
         }