test: try to unflaky test-profile.t

That test rely on timing measurement, because it is about timing measurement. We
try to filter out the most common source of flakyness (slow disk stating)

tests/test-profile.t

@@ -87,7 +87,7 b' statistical profiler works'
 Various statprof formatters work
 
   $ hg --profile --config profiling.statformat=byline sleep 2>../out || cat ../out
-  $ head -n 3 ../out
+  $ grep -v _path_stat ../out | head -n 3
     %   cumulative      self          
    time    seconds   seconds  name    
   * sleepext.py:*:sleep (glob)