Remove fish special grep config

Not needed since I use bash as a default shell and enter
fish manually.

init-package/init-grep.el

@@ -1,10 +0,0 @@
-(use-package grep
-  :init
-  (progn 
-    ;; add fish shell compatibility with grep command
-    (defadvice grep-compute-defaults
-      (after grep-default-fish-compatibility)
-      (grep-apply-setting 'grep-find-command "find . ! -name \"*~\" ! -name \"#*#\" -type f -print0 | xargs -0 -e grep -nH -e ")
-      (grep-apply-setting 'grep-find-template (replace-regexp-in-string "\s{\}\s" " \"{}\" " grep-find-template)))
-    (ad-activate 'grep-compute-defaults)))
-