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/jikes.vim b/runtime/compiler/jikes.vim
index 2d4500e..f12c2cf 100644
--- a/runtime/compiler/jikes.vim
+++ b/runtime/compiler/jikes.vim
@@ -2,6 +2,7 @@
 " Compiler:	Jikes
 " Maintainer:	Dan Sharp <dwsharp at hotmail dot com>
 " Last Change:	2019 Jul 23
+"		2024 Apr 03 by The Vim Project (removed :CompilerSet definition)
 " URL:		http://dwsharp.users.sourceforge.net/vim/compiler
 
 if exists("current_compiler")
@@ -9,10 +10,6 @@
 endif
 let current_compiler = "jikes"
 
-if exists(":CompilerSet") != 2		" older Vim always used :setlocal
-  command -nargs=* CompilerSet setlocal <args>
-endif
-
 " Jikes defaults to printing output on stderr
 CompilerSet makeprg=jikes\ -Xstdout\ +E\ \"%:S\"
 CompilerSet errorformat=%f:%l:%v:%*\\d:%*\\d:%*\\s%m