Vagrantfile can't work with ruby 3.2

`File.exists` was removed from ruby 3.2 [0], and the newest vagrant could use ruby 3.2 and 3.3 [1]. Hence, we should ensure Vagrantfile[2] can work with ruby 3.2+

[0] https://github.com/ruby/ruby/commit/bf97415c02b11a8949f715431aca9eeb6311add2
[1] https://github.com/hashicorp/vagrant/blob/main/vagrant.gemspec#L15
[2] https://github.com/apache/kafka/blob/trunk/Vagrantfile#L62