Evaluate Scaleway ARM64 servers + docker for RPi builds.

For performance of the RPi build process, it may be beneficial to entirely replace the use of the ARMv7-based C1 bare metal servers with ARMv8-based ARM64-2GB VMs from Scaleway.

Theoretically:

• Reduce overall deployment & teardown time, as the allocation of the C1 instances take significant amounts of time.
• AArch64 should offer significantly more performance
• The costs of a C1 and a ARM64-2GB are identical
  • ARM64-4GB scales to 6 cores and 4GB at 2x the cost
  • ARM64-8GB scales to 8 cores and 8GB at 4x the cost
• Docker support is present for AArch64, and viable.
• Making the assumption that the kernel has appropriate mainline support, we should be able to build ARMv6/7 Raspbian images with ease

cc @gitlab-build-team