feat(e2e-tests): model experiment test

[domsolutions]

Summary of changes

• experiment model test for traffic split of 50%/50%
• deploys models and waits for them to be ready
• deploys experiment
• waits for experiment to be ready
• send 20 reqs, there should be at least one response for each model

Checklist

• Added/updated unit tests
• Added/updated documentation
• Checked for typos in variable names, comments, etc.
• Added licences for new files

Testing

[MiguelAAe]

Looks great!