dirstate-v2: no longer register the data-file during transaction

If the data file change during the transaction, we cannot truncate it.

The content of the file itself is fine as it will get backed up at the same time
as the docket.

Leaving the trailing data at the end of failed transaction is fine. The
dirstate-v2 format supports it. The dead data will simply we written over if
necessary.

mercurial/dirstatemap.py

@@ -115,8 +115,6 b' class _dirstatemapcommon:'
             self.parents(), len(packed), meta
         )
         data_filename = new_docket.data_filename()
-        if tr:
-            tr.add(data_filename, 0)
         self._opener.write(data_filename, packed)
         # Write the new docket after the new data file has been
         # written. Because `st` was opened with `atomictemp=True`,