Revert "New key 'M-j' for 'icomplete-mode' (bug#62108)"

This reverts commit 3584a762b8.
Another fix follows shortly after this commit.

etc/NEWS

@@ -3092,10 +3092,6 @@ Meant to be given a global binding convenient to the user.  Example:
 
 ** Icomplete
 
-*** New key 'M-j' for 'icomplete-mode' and 'icomplete-vertical-mode'.
-Like 'M-j' in 'fido-mode', it can exit the minibuffer with a selected
-candidate even when 'icomplete-show-matches-on-no-input' is non-nil.
-
 *** New user options for 'icomplete-vertical-mode'.
 New user options have been added to enhance 'icomplete-vertical-mode':
 

lisp/icomplete.el

@@ -242,7 +242,6 @@ Used to implement the option `icomplete-show-matches-on-no-input'.")
   :doc "Keymap used by `icomplete-mode' in the minibuffer."
   "C-M-i" #'icomplete-force-complete
   "C-j"   #'icomplete-force-complete-and-exit
-  "M-j"   #'icomplete-exit
   "C-."   #'icomplete-forward-completions
   "C-,"   #'icomplete-backward-completions
   "<remap> <minibuffer-complete-and-exit>" #'icomplete-ret)
@@ -456,8 +455,6 @@ if that doesn't produce a completion match."
       (minibuffer-complete-and-exit)
     (exit-minibuffer)))
 
-(defalias 'icomplete-exit #'icomplete-fido-exit)
-
 (defun icomplete-fido-backward-updir ()
   "Delete char before or go up directory, like `ido-mode'."
   (interactive)

lisp/replace.el

@@ -1878,9 +1878,6 @@ is not modified."
          (bound-and-true-p ido-everywhere))
      (substitute-command-keys
       "(\\<ido-completion-map>\\[ido-select-text] to end): "))
-    ((bound-and-true-p icomplete-mode)
-     (substitute-command-keys
-      "(\\<icomplete-minibuffer-map>\\[icomplete-exit] to end): "))
     ((bound-and-true-p fido-mode)
      (substitute-command-keys
       "(\\<icomplete-fido-mode-map>\\[icomplete-fido-exit] to end): "))