Utilise new test helpers expect_webhook_executed and expect_no_webhook_executed within the codebase

About

!100104 (closed) is introducing some new test helpers:

• expect_webhook_executed
• expect_no_webhook_executed

To keep the changes size of that MR down, only the new spec files added are using them.

This issue is to retrospectively fit out other tests to use these helpers. The test MR !98384 (closed) contains these changes.