info: do not output deduplicated_size

No precise refcounting, can't compute that inexpensively.

src/borg/archive.py

@@ -123,7 +123,6 @@ Bytes sent to remote: {stats.tx_bytes}
     def as_dict(self):
         return {
             "original_size": FileSize(self.osize, iec=self.iec),
-            "deduplicated_size": FileSize(self.usize, iec=self.iec),
             "nfiles": self.nfiles,
             "hashing_time": self.hashing_time,
             "chunking_time": self.chunking_time,

src/borg/archiver/info_cmd.py

@@ -43,7 +43,6 @@ class InfoMixIn:
                 Command line: {command_line}
                 Number of files: {stats[nfiles]}
                 Original size: {stats[original_size]}
-                Deduplicated size: {stats[deduplicated_size]}
                 """
                     )
                     .strip()