Upgrade docker tests dind version

What does this MR do?

• Upgrades some tests to use latest Docker image.
• Docker image now requires TLS, so had to make adjustments to cater for this.
• K3S was using an older docker, so also needed updating.

Why was this MR needed?

Our Runner's SaaS COS image was upgraded, which is incompatible with older versions of dind images.

What's the best way to test this MR?

Pipeline should pass.

What are the relevant issue numbers?