taskwarrior: don't create dataLocation with home.file

With

  programs.taskwarrior.dataLocation = /absolute/path

(outside of $HOME) the current implementation wrongly creates
$HOME/absolute/path (due to how home.file is implemented).

Since taskwarrior creates the dataLocation automatically on first run,
there is actually no need for HM to create that directory.

Additional benefit, the .keep symlink that HM creates as a side-effect
no longer appears in the taskwarrior data directory.

Fixes #2207.

(cherry picked from commit 6c984bd675)

modules/programs/taskwarrior.nix

@@ -98,8 +98,6 @@ in {
   config = mkIf cfg.enable {
     home.packages = [ pkgs.taskwarrior ];
 
-    home.file."${cfg.dataLocation}/.keep".text = "";
-
     home.file.".taskrc".text = ''
       data.location=${cfg.dataLocation}
       ${includeTheme cfg.colorTheme}