[Test] Different working directories for package and individual test to be cleaned up

[mnyamunda-scottlogic]

in system test we have a test that captures the .webp images inside system_tests -> data_textures.
With the incorrect working directory setup, the test will fail due to the actual images appearing inside data_textures outside of system_tests.

Currently setup:

data_textures suite must have working directory: /air-quality-backend/system_tests/data_textures
test__that_each_variable_has_correct_key_values -> system_tests
test__that_21_documents_are_fetched -> system_tests
test__that_rendered_bitmaps_are_consistent -> system_tests