ci: fix multus installation

[zhangzujian]

Multus now requires a Kubernetes CNI plugin has been installed first. This patch fixes occasional multus installation failure.

• Make sure you have followed Kube-OVN Code Style.

What type of this PR

• CI

Which issue(s) this PR fixes:

Fixes #(issue-number)

WHAT

🤖 Generated by Copilot at cb744d8

This pull request simplifies and improves the GitHub workflows and the Makefile for building and testing Kube-OVN. It also ensures that Multus is installed before applying a load balancer service to a pod network.

🤖 Generated by Copilot at cb744d8

Multus and OVN
moved to build-x86-image
workflow streamlined

HOW

🤖 Generated by Copilot at cb744d8

• Simplify the installation of Multus and Kube-OVN in the build-x86-image.yaml workflow file by using the kind-install-lb-svc target in the Makefile (link, link)
• Modify the kind-install-lb-svc target in the Makefile to use the kind-install target with flags and add the kind-install-multus target as a dependency (link)
• Remove an empty line from the build-x86-image.yaml workflow file for formatting (link)

[github-actions]

• The commit message should be more descriptive and informative.
• The removal of the Install Multus step in the kubevirt-e2e job seems to be a mistake as it is still present in the scheduled-e2e job. This inconsistency should be addressed.
• The kind-install-lb-svc target in the Makefile should be updated to include both kind-install-multus and kind-install with the appropriate flags.