fish: Completion script rewrite (SHIFT-TAB)

test/lib/common.fish

@@ -3,10 +3,9 @@ set -e FZF_DEFAULT_COMMAND FZF_DEFAULT_OPTS FZF_DEFAULT_OPTS_FILE FZF_TMUX FZF_T
 set -e FZF_CTRL_T_COMMAND FZF_CTRL_T_OPTS FZF_ALT_C_COMMAND FZF_ALT_C_OPTS FZF_CTRL_R_OPTS
 set -e FZF_API_KEY
 # Unset completion-specific variables
-set -e FZF_COMPLETION_TRIGGER FZF_COMPLETION_OPTS
+set -e FZF_COMPLETION_OPTS FZF_EXPANSION_OPTS
 
 set -gx FZF_DEFAULT_OPTS "--no-scrollbar --pointer '>' --marker '>'"
-set -gx FZF_COMPLETION_TRIGGER '++'
 set -gx fish_history fzf_test
 
 # Add fzf to PATH