Hide the details of IUK errors by default

The technical details of the error will be of little use for most user. It is mainly displayed to be copy & pasted for debugging purpose. So we should hide it by default and have a expandable area and a “Show technical details” button or similar.

But at least for a while, such errors should be reported as a bug. It will be nicer this way once this code is tested more
broadly, that is, after it is enabled by default, and most bugs are fixed.

Let’s implement this once such errors will be more likely to be caused by issues on the user’s side (e.g. network problems) than by bugs in our software.

Feature Branch: feature/6508-incremental-upgrades-phase-four

Parent Task: #6508 (closed)

Original created by @sajolida on 6505 (Redmine)