sync: fix temporary name when create a file

[davies]

This PR also fixed a but that may leak temporary file when Create() returns an error but the file is created.

close #4212

[codecov]

Codecov Report

Attention: 9 lines in your changes are missing coverage. Please review.

Comparison is base (9a40759) 55.57% compared to head (ddd310f) 54.13%.
Report is 5 commits behind head on main.

Files	Patch %	Lines
pkg/object/file.go	70.00%	2 Missing and 1 partial ⚠️
pkg/object/nfs.go	72.72%	2 Missing and 1 partial ⚠️
pkg/object/sftp.go	70.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4215      +/-   ##
==========================================
- Coverage   55.57%   54.13%   -1.44%     
==========================================
  Files         154      121      -33     
  Lines       39492    31127    -8365     
==========================================
- Hits        21949    16852    -5097     
+ Misses      15085    12266    -2819     
+ Partials     2458     2009     -449     

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