vagrant: clean up/fix provisioning script

[geyslan]

1. Explain what the PR does

bed3862 vagrant: clean up/fix provisioning script _{(2023/jun/07) Geyslan Gregório <geyslan@gmail.com>}

The commit includes some changes to the provisioning script:
- Added the 'vb.cpus = 4'.
- Added the 'export DEBIAN_FRONTEND=noninteractive' line to silence
  warnings.
- Formatted string expansion in some commands.
- Removed unnecessary 'sudo' commands.
- Fixed the 'kubectl' installation process.
  It was previously using a deprecated path. Now it uses the
  official one.
- Fixed Go's binary path to the 'PATH' environment variable in the
  Vagrant user's '.profile'.
  It was previously not being expanded by using single quotes.
- Added Go's binary path to the 'PATH' environment variable in the
  root user's '.bashrc'.
- Modified the '/etc/sudoers.d/vagrant' file to include 'secure_path'
  variable with Go's binary path.

These changes enhance the development environment for the Vagrant box
and fix some issues that were present in the previous version.

2. Explain how to test it

vagrant destroy (backup your local changes as you wish)
vagrant up
vagrant ssh
make all
make test-unit
make test-integration

3. Other comments

[rafaeldtinoco]

LGTM

[rafaeldtinoco]

LGTM