Expand QA test for Start Instance Anywhere

[korthout]

Description

This is the follow-up of

• Add client integration tests for process instance modification #10371 (comment)

The process instance creation with start instructions (or Start Instance Anywhere) feature already has an end-to-end integration test, introduced with

• Respond rejection on start instance to client on failure to subscribe to events #10353

However, we identified that additional assertions can be made to improve this test. Specifically:

We could extend the test cases to verify that all given instructions are applied. It is not about verifying the logic exhaustively but to confirm that all command arguments are passed from the client to the broker.

A similar test was expanded for process instance modification

• 2f899c0