Add Product Analytics Python SDK events test

What does this MR do and why?

Adding a test for Product Analytics to check that events from Python SDK are processed and shown on Product Analytics dashboards. This test is to be run only for product-analytics/devkit for now. This test is needed to verify events from Python SDK are sent to Product Analytics and processed successfully by its pipelines.

Devkit CI job using custom gitlab-ee-qa from this branch - https://gitlab.com/gitlab-org/analytics-section/product-analytics/devkit/-/jobs/7045789157

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Screenshot of the test passing in product analytics devkit CI

How to set up and validate locally

Not required. Please refer to this guide if you like to run the test locally.

Note the following:

• PA_COLLECTOR_HOST variable should be set to http://caddy:80 when running locally.
• For PythonSdkApp class set @host_name = 'localhost' when running locally against GKD.