STYLE: adjust tutorial Allclean scripts (issue #310)

- A few without a 'cd' at the start.
  Several remove files that are already covered by the cleanCase function.

tutorials/basic/potentialFoam/pitzDaily/Allclean

@@ -4,8 +4,7 @@ cd ${0%/*} || exit 1    # Run from this directory
 # Source tutorial clean functions
 . $WM_PROJECT_DIR/bin/tools/CleanFunctions
 
-rm -rf 0 > /dev/null 2>&1
-
 cleanCase
+rm -rf 0
 
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