runtime: Remove fallback :CompilerSet definition from compiler plugins

The :CompilerSet command was added in version Vim 6.4 which was released
twenty years ago.  Other runtime files do not support versions of that
vintage so it is reasonable to remove this fallback command definition
now.

closes: #14399

Signed-off-by: Doug Kearns <dougkearns@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/compiler/tex.vim b/runtime/compiler/tex.vim
index 0925d17..9d8c660 100644
--- a/runtime/compiler/tex.vim
+++ b/runtime/compiler/tex.vim
@@ -3,6 +3,7 @@
 " Maintainer:   Artem Chuprina <ran@ran.pp.ru>
 " Contributors: Enno Nagel
 " Last Change:  2024 Mar 29
+"		2024 Apr 03 by The Vim Project (removed :CompilerSet definition)
 
 if exists("current_compiler")
 	finish
@@ -10,10 +11,6 @@
 let s:keepcpo= &cpo
 set cpo&vim
 
-if exists(":CompilerSet") != 2		" older Vim always used :setlocal
-  command -nargs=* CompilerSet setlocal <args>
-endif
-
 " If makefile exists and we are not asked to ignore it, we use standard make
 " (do not redefine makeprg)
 if exists('b:tex_ignore_makefile') || exists('g:tex_ignore_makefile') ||