Improvements to how tests that are being run manually are reassigned after start

[ccanash]

@ccanash @howard-e

This is looking great in staging. Definitely shippable. I found one issue that could either be addressed before ship or you could raise a separate issue so it can be addressed later. I don't think multiple assignments will be common, and the content is still perceivable; addressing before ship is more a matter of preventing AX debt, so decide based on LOE and capacity.

Issue: List semantics and phrase separation are missing when there are multiple entries in the Tester Assignment History for a test plan run
Description: When there are multiple reassignments of run ownership, the history is presented as multiple spans. As a result, for a screen reader user, all the assignments are combined into a single long string like:

This run was reassigned from 'mcking65' to 'ChrisC' on 20 Oct 2025 15:54Performed by: mcking65This run was reassigned from 'LouisDo10' to 'mcking65' on 20 Oct 2025 15:49Performed by: mcking65

Instead, each assignment should be a separate list item and there should be a ". " after the timestamp, e.g.:

• This run was reassigned from 'mcking65' to 'ChrisC' on 20 Oct 2025 15:54. Performed by: mcking65
• This run was reassigned from 'LouisDo10' to 'mcking65' on 20 Oct 2025 15:49. Performed by: mcking65

There is an opportunity for simplification by removing the word "Performed", the ":" after "by", and putting single quotes around the ID of the person who performed the re-assignment:

• This run was reassigned from 'mcking65' to 'ChrisC' on 20 Oct 2025 15:54 by 'mcking65'.
• This run was reassigned from 'LouisDo10' to 'mcking65' on 20 Oct 2025 15:49 by 'mcking65'.

Originally posted by @mcking65 in #1369