`brew cleanup` removes the current version of `portable-ruby` about brew

[Bo98]

We could probably move some of the Linux-specific code

brew/Library/Homebrew/extend/os/linux/cleanup.rb

Lines 11 to 19 in 754c026

	rubies = [which("ruby"), which("ruby", ORIGINAL_PATHS)].compact
	system_ruby = Pathname.new("/usr/bin/ruby")
	rubies << system_ruby if system_ruby.exist?
	check_ruby_version = HOMEBREW_LIBRARY_PATH/"utils/ruby_check_version_script.rb"
	rubies.uniq.any? do |ruby|
	quiet_system ruby, "--enable-frozen-string-literal", "--disable=gems,did_you_mean,rubyopt",
	check_ruby_version, RUBY_VERSION
	end

to be generic code and then make the macOS one defer to the generic code if that env is set

[MikeMcQuaid]

Step-by-step reproduction instructions (by running brew commands)

brew developer on
brew update
brew cleanup

@carlocab cannot reproduce on latest master:

$ brew update; brew cleanup
==> Updating Homebrew...
Already up-to-date.
Removing: /opt/workbrew/home/Library/Caches/Homebrew/bootsnap... (524 files, 4.1MB)
==> This operation has freed approximately 4.1MB of disk space.

$ brew --version
Homebrew 4.3.5-95-g24f74c0
Homebrew/homebrew-core (git revision da9db7107e3; last commit 2024-06-14)
Homebrew/homebrew-cask (git revision 718a0c3774; last commit 2024-06-14)

[carlocab]

Caused by HOMEBREW_USE_RUBY_FROM_PATH -- this needs to be unset.