ci: update CI Vagrant VM IP addresses

[nbusseneau]

VirtualBox 6.1.28 introduced new restrictions on host-only networking: https://www.virtualbox.org/wiki/Changelog-6.1#v28
Manual: https://www.virtualbox.org/manual/ch06.html#network_hostonly

On Linux, Mac OS X and Solaris Oracle VM VirtualBox will only allow IP addresses in 192.68.56.0/21 range to be assigned to host-only adapters. For IPv6 only link-local addresses are allowed. If other ranges are desired, they can be enabled by creating /etc/vbox/networks.conf and specifying allowed ranges there. For example, to allow 10.0.0.0/8 and 192.168.0.0/16 IPv4 ranges as well as 2001::/64 range put the following lines into /etc/vbox/networks.conf:

 * 10.0.0.0/8 192.168.0.0/16
 * 2001::/64

Lines starting with the hash # are ignored. Next example allows any addresses, effectively disabling range control:

 * 0.0.0.0/0 ::/0

These new restrictions manifest in the form of the following issue:

VBoxManage: error: Code E_ACCESSDENIED (0x80070005) - Access denied (extended info not available)
VBoxManage: error: Context: "EnableStaticIPConfig(Bstr(pszIp).raw(), Bstr(pszNetmask).raw())" at line 242 of file VBoxManageHostonly.cpp

when running VBoxManage hostonlyif ipconfig command where the IP address is outside of the allowed range, as is the case in our CI:

10:32:07  ==> k8s1-1.21: Clearing any previously set network interfaces...
10:32:09  There was an error while executing `VBoxManage`, a CLI used by Vagrant
10:32:09  for controlling VirtualBox. The command and stderr is shown below.
10:32:09
10:32:09  Command: ["hostonlyif", "ipconfig", "vboxnet0", "--ip", "192.168.38.1", "--netmask", "255.255.255.0"]
10:32:09
10:32:09  Stderr: VBoxManage: error: Code E_ACCESSDENIED (0x80070005) - Access denied (extended info not available)
10:32:09  VBoxManage: error: Context: "EnableStaticIPConfig(Bstr(pszIp).raw(), Bstr(pszNetmask).raw())" at line 242 of file VBoxManageHostonly.cpp

We update the IP addresses used by Vagrant VMs to be compatible with the new restricted range so that our VMs can still be run when using VirtualBox 6.1.28 and above, without the need for the /etc/vbox/networks.conf workaround above.

[nbusseneau]

This is a re-open of #17733, which was merged accidentally and subsequently reverted in #17898.

[nbusseneau]

Original PR hit issues:

• On 1.16 net-next tests (ci: update CI Vagrant VM IP addresses #17733 (comment)), however the re-run seems to have gotten through just fine (see checks below): https://jenkins.cilium.io/job/Cilium-PR-K8s-1.16-net-next/1953/
• On runtime tests, tracked in CI: RuntimePrivilegedUnitTests Run Tests #17897.

[nbusseneau]

Reposting comment from previous PR regarding the "IP replace pattern":

My pattern was:

• Try to do 3X => 5X if possible => this perfectly matches the CI Vagrant VMs IPs.
• Start from 60 if not possible => this perfectly matches the non-CI Vagrant VMs IPs.

But I can re-do it another way if we'd like, I mostly wanted to have a quick thing out to run tests ^^

[pchaigno]

There's a suspicion that the privileged unit test failure could actually be caused by this PR so let's retrigger to see:
/test-runtime

[pchaigno]

The changes here mostly impact @cilium/ci-structure (test VMs) and @cilium/contributing (dev. VMs); other changes are trivial. So probably not worth waiting for all remaining review requests. Tests are also all passing. Marking ready to merge.