Merge pull request #19015 from Homebrew/fix-disabled-envvar-message

env_config: Improve the deprecated envvar message

Library/Homebrew/env_config.rb

@@ -527,9 +527,8 @@ module Homebrew
 
           falsy_values = %w[false no off nil 0]
           if falsy_values.include?(env_value&.downcase)
-            odeprecated "#{env}=#{env_value}", <<~EOS
-              If you wish to enable #{env}, #{env}=1
-              If you wish to disable #{env}, #{env}=
+            odeprecated "#{env}=#{env_value}", <<~EOS.chomp
+              #{env}=1 to enable and #{env}= (an empty value) to disable
             EOS
           end