vagrant: Install temporary forked bpftool

Provisioning of the Vagrant development environment fails due to the
missing forked bpftool:

  $ ./contrib/vagrant/start.sh
  [...]
  runtime1: Feb 13 17:26:23 runtime1 cilium-agent[20863]: level=error msg="Command execution failed" cmd="[bpftool -j feature probe filter_out \\(trace\\|write_user\\)]" error="exit status 255" subsys=probes
  runtime1: Feb 13 17:26:23 runtime1 cilium-agent[20863]: level=warning msg="{\"error\":\"expected no more arguments, 'kernel', 'dev', 'macros' or 'prefix', got: 'filter_out'?\"}" subsys=probes
  runtime1: Feb 13 17:26:23 runtime1 cilium-agent[20863]: level=fatal msg="could not run bpftool" error="exit status 255" subsys=probes
  runtime1: Cilium failed to start
  [...]

This provisioning failure was introduced by #10164. Cilium now expects
bpftool to be Cilium's (temporary) forked version, but the VirtualBox VM
has the upstream bpftool. This commit installs the forked bpftool as part
of the Vagrant provisioning.

Signed-off-by: Paul Chaignon <paul@cilium.io>

Vagrantfile

@@ -110,6 +110,10 @@ ENV["LC_ALL"] = "en_US.UTF-8"
 ENV["LC_CTYPE"] = "en_US.UTF-8"
 
 Vagrant.configure(2) do |config|
+    if ENV['CILIUM_TEMP'] then
+        # Temporarily install forked bpftool
+        config.vm.provision "shell", path: "#{ENV['CILIUM_TEMP']}/../../test/provision/bpftool.sh"
+    end
     config.vm.provision "bootstrap", type: "shell", inline: $bootstrap
     config.vm.provision "build", type: "shell", run: "always", privileged: false, inline: $build
     config.vm.provision "install", type: "shell", run: "always", privileged: false, inline: $install