Update shortest path test to use API

[ajbalogh]

Describe the bug
Currently the shortest path test does not use the APIs to annotate the graph and query the graph for shortest path

To Reproduce
See the https://github.com/Keysight/infragraph/blob/main/src/tests/test_shortest_path.py test

Expected behavior

• The test must only use publicly documented APIs present in the openapi.yaml document.
• the infragraph service code should not have public members that are not present in the openapiart generated base API class