Tests: Switch to Fedora-25 for packaging tests

Switch the Fedora Vagrant box for packaging tests to Fedora-25 as
Fedora-24 will become EOL one month after Fedora-26 is out.

Relates #24466

Vagrantfile

@@ -56,8 +56,8 @@ Vagrant.configure(2) do |config|
     config.vm.box = "elastic/oraclelinux-7-x86_64"
     rpm_common config
   end
-  config.vm.define "fedora-24" do |config|
-    config.vm.box = "elastic/fedora-24-x86_64"
+  config.vm.define "fedora-25" do |config|
+    config.vm.box = "elastic/fedora-25-x86_64"
     dnf_common config
   end
   config.vm.define "opensuse-13" do |config|