Docker files clean up and unit test coverage

[santhoshatdell]

Description

• Cleaned up unused docker files in the powerstore repository. There is only one Dockerfile now for the main build.
• Some refactoring for k8sutils functions in how the k8s client set is created and passed.
• Added unit tests for the missed k8sutils pkg for code coverage check.

GitHub Issues

List the GitHub issues impacted by this PR:

GitHub Issue #
dell/csm#1691

Checklist:

• I have performed a self-review of my own code to ensure there are no formatting, vetting, linting, or security issues
• I have verified that new and existing unit tests pass locally with my changes
• I have not allowed coverage numbers to degenerate
• I have maintained at least 90% code coverage
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• Backward compatibility is not broken

How Has This Been Tested?

Image is built successfully.

[root@master-1-SPknwwOOoaVwH csi-powerstore]# make docker
which: no gosec in (/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/usr/local/go/bin:/usr/local/go/bin:/go/bin:/usr/local/go/bin:/go/bin)
go run core/semver/semver.go -f mk >semver.mk
make -f docker.mk DOCKER_FILE=Dockerfile docker
..........
Dockerfile
podman build --pull -f Dockerfile -t "dellemc/csi-powerstore:v2.13.0" --build-arg GOIMAGE=golang:1.23 --build-arg BASEIMAGE=quay.io/dell/container-storage-modules/csm-base-image:nightly .
[1/2] STEP 1/5: FROM golang:1.23 AS builder
..........
Successfully tagged localhost/dellemc/csi-powerstore:v2.13.0

[santhoshatdell]

FAIL: coverage for package github.com/dell/csi-powerstore/v2/pkg/common/k8sutils is 0.0%, lower than 90%

I will look into this.