fix set_writable to not modify no_write_can_delete

Go's MarkVolumeWritable only sets noWriteOrDelete=false and persists.
Rust was additionally setting no_write_can_delete=has_remote_file,
which could incorrectly change the write mode for remote-file volumes
when the master explicitly asks to make the volume writable.

seaweed-volume/src/storage/volume.rs

@@ -2070,7 +2070,6 @@ impl Volume {
     /// Mark this volume as writable (allow writes and deletes).
     pub fn set_writable(&mut self) -> Result<(), VolumeError> {
         self.no_write_or_delete = false;
-        self.no_write_can_delete = self.has_remote_file;
         self.save_vif()
     }