Fixed #22294 -- Prevented converting length filter output to string

Thanks Steve Pike for the report.
Fixed #22256 -- Replaced bad fallback for missing PATH

Thanks Baptiste Mispelon for the review.
Fixed #22241 -- Selectively added line breaks in admin read-only fields

When content is supposed to contain HTML, we do not try to add
line breaks in read-only contents.
Thanks Alexander Todorov for the report.
Fixed a failing test introduced in 918a16bc4c099ab0cae72a231de3e99e2a9d02cb.

Refs #22307.