[python-experimental] Adds response body tests for json content type

[spacether]

[python-experimental] Adds response body tests for json content type for the v3.0.3 unit test spec
coverage updated from 86% to 89% for the unit-test-api for python-experimental
Add positive test for: should_not_look_in_applicators_request_body + should_not_raise_error_when_float_division to increase coverage for those endpoint
Adds a api_test_partial template
dead code removed from schemas.py

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