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/raco.vim b/runtime/compiler/raco.vim
index bd10859..d35d86b 100644
--- a/runtime/compiler/raco.vim
+++ b/runtime/compiler/raco.vim
@@ -3,12 +3,9 @@
 " Maintainer:   D. Ben Knoble <ben.knoble+github@gmail.com>
 " URL:          https://github.com/benknoble/vim-racket
 " Last Change: 2022 Aug 12
+"		2024 Apr 03 by The Vim Project (removed :CompilerSet definition)
 
 let current_compiler = 'raco'
 
-if exists(":CompilerSet") != 2
-  command -nargs=* CompilerSet setlocal <args>
-endif
-
 CompilerSet makeprg=raco
 CompilerSet errorformat=%f:%l:%c:%m