[JUJU-1195]rewrite to bash based nw clouds display test

[basebandit]

This is part of the effort to migrate python based tests to bash based tests for ease of maintenance and simplicity.

Checklist

• [x] Code style: imports ordered, good names, simple structure, etc
• ~[ ] Comments saying why design decisions were made~
• ~[ ] Go unit tests, with comments saying what you're testing~
• [x] Integration tests, with comments saying what you're testing
• ~[ ] doc.go added or updated in changed packages~

QA steps

cd tests
make build && make install
./main.sh cli run_assess_clouds
./main.sh cli run_assess_show_cloud