patch 9.1.0899: default for 'backspace' can be set in C code

Problem:  default for 'backspace' can be set in C code
Solution: promote the default for 'backspace' from defaults.vim to the C
          code (Luca Saccarola)

closes: #16143

Signed-off-by: Luca Saccarola <github.e41mv@aleeas.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/defaults.vim b/runtime/defaults.vim
index 82f3358..38b03da 100644
--- a/runtime/defaults.vim
+++ b/runtime/defaults.vim
@@ -1,7 +1,7 @@
 " The default vimrc file.
 "
 " Maintainer:	The Vim Project <https://github.com/vim/vim>
-" Last Change:	2024 Nov 14
+" Last Change:	2024 Dec 01
 " Former Maintainer:	Bram Moolenaar <Bram@vim.org>
 "
 " This is loaded if no vimrc file was found.
@@ -33,9 +33,6 @@
   set nocompatible
 silent! endwhile
 
-" Allow backspacing over everything in insert mode.
-set backspace=indent,eol,start
-
 set ruler		" show the cursor position all the time
 set showcmd		" display incomplete commands