test-network-k8s: Improve prereqs logic

[satota2]

It seems that PR #1205 has stalled, so I have created a new PR that builds upon the considerations from that one while addressing the issues raised.

This PR resolves issue #1204 and also addresses the concerns mentioned in PR #1205. Specifically, it:

• Uses the newer install script instead of bootstrap.sh.
• Downloads binaries corresponding to the image versions, supporting both two-digit and three-digit Fabric version specifications.

Related issue: Resolves #1204