Use a unique filename to save temp ckpt in tuner

[rohitgr7]

What does this PR do?

Fixes #9574

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[tchaton]

LGTM !

[codecov]

Codecov Report

Merging #9682 (44b1c25) into master (41e3be1) will increase coverage by 0%.
The diff coverage is 100%.

@@          Coverage Diff           @@
##           master   #9682   +/-   ##
======================================
  Coverage      93%     93%           
======================================
  Files         179     179           
  Lines       15306   15308    +2     
======================================
+ Hits        14199   14201    +2     
  Misses       1107    1107