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/multiphase/interFoam/RAS/waterChannel/Allclean

@@ -4,7 +4,9 @@ cd ${0%/*} || exit 1    # Run from this directory
 # Source tutorial clean functions
 . $WM_PROJECT_DIR/bin/tools/CleanFunctions
 
+cleanCase
+
 rm 0/alpha.water.gz 0/alpha.water 2>/dev/null
 rm -rf *Flux
 
-cleanCase
+#------------------------------------------------------------------------------