Test fix for Networking tests

[shubhamsg199]

Description of changes

Adding choices for parameter_type field as it was populating random string for parameter_type causing Networking tests to fail

$ pytest tests/foreman/api/test_subnet.py
========================================= test session starts =================================================================
platform linux -- Python 3.11.1, pytest-7.2.1, pluggy-1.0.0
shared_function enabled - OFF - scope:  - storage: file
rootdir: /home/sganar/satellite/robottelo, configfile: pyproject.toml
plugins: xdist-3.1.0, services-2.2.1, mock-3.10.0, cov-3.0.0, reportportal-5.1.3, ibutsu-2.2.4
collected 47 items / 7 deselected / 40 selected                                                                                                                                                                                                                                          

tests/foreman/api/test_subnet.py ........................................                                                                                                                                                                                                          [100%]

================================= 40 passed, 7 deselected  in 157.55s (0:02:37) =======================================================

[shubhamsg199]

trigger: test-robottelo
pytest: tests/foreman/api/test_subnet.py

[shweta83]

Ack