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/javac.vim b/runtime/compiler/javac.vim
index 8507efd..f5fe841 100644
--- a/runtime/compiler/javac.vim
+++ b/runtime/compiler/javac.vim
@@ -1,17 +1,13 @@
 " Vim compiler file
 " Compiler:	Java Development Kit Compiler
 " Maintainer:	Doug Kearns <dougkearns@gmail.com>
-" Last Change:	2019 Oct 21
+" Last Change:	2024 Apr 03
 
 if exists("current_compiler")
   finish
 endif
 let current_compiler = "javac"
 
-if exists(":CompilerSet") != 2		" older Vim always used :setlocal
-  command -nargs=* CompilerSet setlocal <args>
-endif
-
 let s:cpo_save = &cpo
 set cpo&vim