Revert "Enable red dots during completion by default".

After a few weeks of using this, I'd prefer this to not be enabled by default. My bad for suggesting that in the first place.

This reverts commit fc49b4a4de.

lib/completion.zsh

@@ -59,7 +59,7 @@ zstyle ':completion:*:*:*:users' ignored-patterns \
 # ... unless we really want to.
 zstyle '*' single-ignored show
 
-if [ "$DISABLE_COMPLETION_WAITING_DOTS" != "true" ]; then
+if [ "x$COMPLETION_WAITING_DOTS" = "xtrue" ]; then
   expand-or-complete-with-dots() {
     echo -n "\e[31m......\e[0m"
     zle expand-or-complete