Increase subctl unit test coverage

[dfarrell07]

We now have easy insight into unit test coverage via SonarCloud. The current UT coverage for the submariner-io/subctl repo is 3%. We should strive to improve UT coverage, ideally initially up to at least 70%.

https://sonarcloud.io/summary/overall?id=submariner-io_subctl
https://sonarcloud.io/component_measures?id=submariner-io_subctl&metric=coverage&view=list

[stale]

This issue has been automatically marked as stale because it has not had activity for 60 days. It will be closed if no further activity occurs. Please make a comment if this issue/pr is still valid. Thank you for your contributions.