Fix: add json output, upgrade libraries and removes unsupported tests

[ritwikranjan]

This pull request includes several updates to the network/benchmarks/netperf project, focusing on improving Dockerfile configuration, Makefile commands, and Kubernetes client interactions. The changes also include enhancements to the launch.go file to support JSON output and use context for Kubernetes API calls.

This tracks issue kubernetes#2876

Dockerfile and Makefile Updates:

• Updated the Dockerfile to use golang:bullseye and simplified file copying steps.
• Modified the Makefile to streamline the docker target and added a localtest target for local testing. [1] [2]

.gitignore Updates:

• Added .json and kubeConfig to the .gitignore file to exclude these files from version control. [1] [2]

go.mod Updates:

• Updated dependencies in go.mod to newer versions, ensuring compatibility with Go 1.23.

launch.go Enhancements:

• Added support for JSON output alongside CSV data and used context for all Kubernetes API calls to improve code reliability and readability.

nptest.go Fixes:

• Comment out qperf and iperf SCTP tests as they do not work with the current framework.
• Adds some throuput tests that produce json output, we can extract those using the -json in launch.go