Editing test step attachments should not affect previous test runs

Current behavior: Currently, when a test step attachment is changed in the test definition, all previous test runs reflect the updated attachment. While this is the current design, it can be misleading for users reviewing past executions, as it no longer shows the attachment that was originally used.

Suggested behavior: Consider preserving the original attachment in existing Test Runs when a Test Step is edited. Only future Test Runs should reflect the updated attachment. This would improve traceability and ensure that past executions remain accurate representations of what was actually tested.