Write just ./.version on all components

This way it's easier to get right. See previous commit.

(cherry picked from commit 3556f6bf4c)

tests/functional/package.nix

@@ -75,16 +75,10 @@ mkMesonDerivation (
     ];
 
     preConfigure =
-      # "Inline" .version so it's not a symlink, and includes the suffix.
-      # Do the meson utils, without modification.
-      ''
-        chmod u+w ./.version
-        echo ${version} > ../../../.version
-      ''
       # TEMP hack for Meson before make is gone, where
       # `src/nix-functional-tests` is during the transition a symlink and
       # not the actual directory directory.
-      + ''
+      ''
         cd $(readlink -e $PWD)
         echo $PWD | grep tests/functional
       '';