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/yamllint.vim b/runtime/compiler/yamllint.vim
index 889b04b..88e2efb 100644
--- a/runtime/compiler/yamllint.vim
+++ b/runtime/compiler/yamllint.vim
@@ -2,15 +2,12 @@
 " Compiler:    Yamllint for YAML
 " Maintainer:  Romain Lafourcade <romainlafourcade@gmail.com>
 " Last Change: 2021 July 21
+"		2024 Apr 03 by The Vim Project (removed :CompilerSet definition)
 
 if exists("current_compiler")
     finish
 endif
 let current_compiler = "yamllint"
 
-if exists(":CompilerSet") != 2
-    command -nargs=* CompilerSet setlocal <args>
-endif
-
 CompilerSet makeprg=yamllint\ -f\ parsable