Restore correct keyboard shortcut for Replace in Files on the Mac

#8623 inadvertently changed the keyboard shortcut for Replace in Files on the Mac from Cmd-Alt-Shift-F to Ctrl-Alt-Shift-F. I think the issue is that if you don't specify a platform for the shortcut, we translate Ctrl to Cmd on the Mac, but if you specifically list a shortcut as a Mac shortcut, we don't translate Ctrl (since we assume you really mean the Mac Ctrl key). This restores the shortcut.

@RaymondLim @JeffryBooher Could one of you review and merge?